I have been reading all the comments here and I am greatly concerned about the ownership of dogs by people who do not understand what socialization, defense/guard and protection really means in the life of a working breed dog.  Ojeriza is a term most often used in specific recognition of the Fila Brasilero/Brazilian Mastiff.  The other breeds including the mastiffs are described as an "aloofness" to strangers.  The Fila is known to go beyond this to an expressed hatred of strangers big difference in temperament characteristic. 

I have one of three males from the same litter.  At one time my family had all three males.  My Yogi is now the only one left out of the litter.  The largest at birth was Louie the Lips - we actually took ownership of him at 6 months as a rescue he had been sold to people who stupidly used him as bait for fighting pit bulls and Cane Corso's need I describe his temperament to anyone knows what a 6 month old Brazilian is like?  He weighed in at 95 pounds was 26 inches to the shoulder the most beautiful burgundy color and this precious soul rode 7 1/2 hours in the back seat with me laying over him and his brother Yogi the Bear.  Their brother owned by my son Vinnie de Smooch was awaiting their reunion at home.  Louie died when he received his vaccinations the previous owner did not get his puppy shots the rabies vaccine activated the parvo vaccine and our beloved Lips died receiving medical care at our veterinarian.  He was an amazing animal.  He was loving, he adjusted to his new surroundings and family including my then 4 year old grandson and the Ojeriza was not only present it was active.  He did not want strangers around and it took more than 10 feet it was out of scent of sight detection.  He would stand guard at scent and at sight he was in defense. 

Vinnie de Smooch had been a very large and very friendly pup, until Louie de Lips moved in.  Louie seemed to teach Vinnie the guard side of his personality and the two of them together were a force to be reckoned with.  Vinnie followed the lead of his big brother and developed a quirky Ojeriza, he liked people he loved faces covered with anything yummy, he was exuberant and full of life and then in the flash of a second he was ready to protect.  Although socialized from 6 weeks, taken to school, inside stores, the dog park, walking in public places, exposed to children, adults everywhere he became unpredictable and dangerous.  He bit three people protecting his family - truly protecting his family and unfairly euthanized.  It is important to remember that on all occasions people were aware he was defending his family and yet they proceeding to provoke him by coming on my son's property, approaching the dog after my son had repeatedly told them not to come near.  He was leashed and under control he bit when the individuals swung at him and attempted to grab him. 

This brings us to Yogi Bear who at 31 inches to the shoulder is the tallest of the three big boys.  He had been the runt, and he shared a special bond with his brothers.  I think to understand Ozeriza and it's development it is important to look at the development of the dogs.  My Yogi like his brother Louie had been sold to persons who abandoned him tied to 12 inches of rope he endured a snow storm and starvation when the neighbors finally noticed that he had been abandoned by the owner of the home they called the breeder who went back and took him home nursing his frozen and starved little self.  Louie was sold to monsters and the breeder was notified and rescued him as well.  I had called to see if they were going to have any more pups because we loved Vinnie he was so wonderful, full of life and absolutely the Belle of the ball he loved everyone.  He was so intelligent and easy to train he would learn anything and look at you like is that your best more please.  When they explained the plight of his two brothers of course I said I am coming to get them. 

Yogi is quite a boy.  My grandchildren can do anything with him.  You see him in the pirate outfit wearing an eye patch, that is nothing my granddaughter paints his nails and puts makeup on him including yes imagine it bright red lipstick it would appear that Uncle Yogi is the perfect fashionista as she develops her "makeup mastery."  Oddly when I first brought him home he was not confident neither was his brother Louie.  Within 24 hours both were standing up, commanding the leash with skill and confidence and working the house finding their boundaries and discovering their territory.  It all happened very quickly.  Yogi actually snarled the first time my grandson hugged him no bite no growl just a quick flip of the lip - a gentle but firm correction (I said no) and he relented to the hug - that was the only time he ever rejected a hug from my grandson he not only welcomes them now but cuddles with the children watching TV or just taking a nap he insists on "cuddling" with them. 

At age 22 months my grandson who was 6 was attacked by a young male who was under the influence of substances Yogi leapt into action.  It is not a sight to behold when your best friend turns into fierce protector - it was both amazing and horribly terrifying.  The end result was that without a single bite he was able to defend, diffuse and contain the threat to my grandson until I could intervene safely. 

My Yogi is not aggressive I have had him temperament tested every year.  He is not an aggressive dog.  He is however a guard dog.  His Ojeriza level is 10 and he is perfectly able to be controlled.  Is he socialized he has been - and it is a great thing.  I had broken my foot severely and was confined to the house for almost a year.  It was Yogi who picked me off the floor and assisted me to the phone so I could call for help when the injury occurred.  That greatly diminished his training time.  I had people come to the house so he would let people in.  Due to a medical treatment I developed PTSD.  That was a wonderful experience that he picked up on and as a result he became very protective of me.  Thanks to the removal of a diseased thyroid, and a non cancerous tumor in my uterus the anxiety and fear I lived with is under control and guess who is much calmer?  He is really great at understanding where I am and providing a safe environment for me.  An environment he can control when I cannot.  That is what a guard dog does. 

I have been training dogs for over 40 years.  If your dog does not like people to the extent that you cannot control that dog there is a problem.  Please don't give me the pack leader theories because I will tell you that while I agree with this there is a part of that pack leader theory that its teachers fail to communicate - the change of the guard.  Pack animals challenge the pack leader for the role of leader and you do not want to get into that conversation with an animal that is intent on doing what it takes often those disputes are to the death.  I think that people forget we cannot control, lead or manipulate everything.  We must learn that trust and bond come by learning who each other is and what our limits are.  My Yogi is well aware that at this point he is stronger than me - and yet he yields to me, if he perceives I am in danger he stands his ground until the threat passes (a neighbor's dog is fence aggressive, lol), I pay attention to his alerts - I face the danger he learns my limits and respects them.  I value his discretion and respond to his signals.  This is how you get a dog with level 10 Ojeriza to control himself.  Is he safe in public - if the public is safe.  Can I control him - yes.  What if he decides to protect me.  Yes, I control him all the time it is the way I present myself if I cannot take control of the situation he will stand over me between me and the present danger - he will do whatever necessary to preserve my safety - if it is a medical situation he just knows and has always allowed emergency staff to treat me.  Guard dog breeds are intelligent and they know instinctively - So I would say stop encouraging people to feed and pet your dog.  Personality traits may dictate that your dog doesn't like being handled by others.  Do all people like being hugged or kissed or you know "socialized".  Yuck!  My big boy is very affectionate this is not always demonstrated by allowing you to slop sugary kisses and booger faced hugs and gooey little chocolate covered fingers all over his glistening coat - well almost always the gooey chocolate covered fingers.  A lot of times he shares his affection by doing his "tricks"  he can count to four yes you can say Yogi what is 1 plus 3 and yes he will bark 4 times.  Yeah, he is a smart bear!  He does have a picnic basket with all his stuff in it he may bring you a brush, a toy or a costume!  He loves to play with people and interact with them.  He may not want to take a treat from a stranger.  Think about that why would you want your best friend to take food from a perfect stranger?  He/she would not let you eat something from a stranger it might be poison - no he/she would give it a good smell or investigation before you would put that in your mouth, and in truth a dog does not eat or drink when they are alarmed, concerned, nervous.  So you are putting a behavior to them that is against their logic.  Sometimes socializing just means letting them be in the moment and refraining from a displayed behavior that is unwanted.  Dogs don't just walk up to each other, they notice each other from a distance, they watch and smell.  They get the picture so to speak.  They introduce theirselves and their intentions. 

The biggest problem with the socialization I have witnessed on this forum is it appears you interpret socialization as the act of forcing a dog to socialize like a human.  How many humans do you really trust.  I think that the desire to have a guard dog comes from a need to feel secure and to have a companion who gives you the ability to maintain a boundary.  There is nothing wrong with that - sometimes Yogi become Cujo that is why I have him.  I would encourage all to enjoy their companions and their distinctive personalities.