Frankly, by the other things, I don't think your imagining is really that far off. Looking into someones diseased mouth! Bleh! xC I always have a deep respect for anyone who goes into oral care and yet a strange fascination in what would ever inspire them to go into that field in the first place.
Again, I don't really understand what would ever make a person want to go "I WANT TO GO LOOK AT PEOPLES UNCLEAN AND DISEASED MOUTHS FOR THE REST OF MY LIFE" and while I know a lot of people are in it for the money, I don't think I personally could handle something like that. Especially when some people in the world could REALLY REALLY use a breath mint. >:I