I was at the Tropicana and there was one dealer there that was an absolute loser. I've never seen a dealer be so obvious and talk about tipping. He even delayed hands until his tip came, talk about rude and unprofessional.
I personally don't tip per pot like everyone else and his attitude is precisely why I tip on a per session basis. The dealer's got to work at getting my tips.
I think it is stupid the way we've all learned to tip on a per pot basis. That means a dealer can be crappy or slow or make tons of mistakes and still get paid every time someone wins a pot. I figure the dealer has to show he's professional, fast, friendly, accurate, and then after every 1/2 hour or so I'll throw him 2-3 bucks.
If we just tip for winning and not for the performance of the dealer, we encourage laziness in dealers, and we're also telling good dealers that we don't care that they are better than weaker dealers.