I've experienced both side of the dentist coin, so to speak. Went to an out-and-out crook whose stock in trade was to tell people that everything was fine, not to worry -- even when they DID have problems. (He told me that a spot I was worried about on my daughter's tooth was just a chip. It wasn't, it was a cavity.)
The fact that it was a cavity was confirmed by a great dentist I found after a lot of searching, who's been wonderful. My daughter has been cavity-free since her fillings almost two years ago, and most importantly,
enjoys going to the dentist.
The first dentist has since been disbarred, or whatever it's called when bad dentists are prohibited from practicing.

(And no, stopdentists, I'm not interested in sueing, nor am I interested in stopping dentists in general. Our current dentist is my hero.)