I happen to tip well at restaurants were the service is good, and tip poorly when the service is poor.
I was at Las Vegas and playing BJ at a $5 table. I won a crazy side bet (3 bucks and won $3000). Anyway, the jerk dealer kept telling me that it was standard to tip at least 20%!, just like a waiter. With that comment he cost himself any tip. Eventhough I had been tipping him on nice hands, etc. What gall to presume you are owed a tip from a patron.
So, does the dealer tip you 20% if you lose 3K?