Dogs that eat a natural diet usually have clean white teeth. kibble tends to stain the teeth much like people who drink coffee or too much wine. I think it is normal for a vet to suggest a cleaning if they think that the condition of the teeth and gums can cause some other septic condition. Personally I would not have my dogs teeth cleaned - I would change their diet. A scam? I don't think so. Just more well meaning humanization of the domestic dog to take money out of your pocket. Next time you are there ask which of the "recommended" shots are actually required by your state or countries laws. We have a dog whose teeth were really discolored because of kibble and were constantly nagged by the vet that they need to be cleaned... we never did. Changed to raw diet and a few months later when we took him for rabies shot the vet wanted to know where we had his teeth cleaned... hehehe .. Nature works wonders.