20/20 (11.22.13) | Video - ABC News
Starts at 9:45 mark.
Yes, some vets recommend unnecessary things and some don't. Another thing to pay attention to is if the vet is also the practice owner. Some bosses insist on certain protocols. Veys either follow them or lose their job. But these vets can give their own ooinion/recommendation if specifically asked.
I wouldn't take my dogs to a vet who pushes annal vaccines. Dentistry is a bit more of a grey area. You really can't know for sure if there is a problem until the dog is asleep. Gingivitis is a good reason for a cleaning, but not the only reason.