Poker Dealers competing w/ Players?

Is it right for a dealer after his shift to sit down at the same table he dealt at all night to play? Is it right for him to make money off the same customers that tipped him all night after seeing how they play and learning their weaknesses? Thoughts??

(Update) I’m a regular at a large well known poker room where this happens. Some of the dealers are real pros and two actually made over 15k this week off the players so the dealers aren’t all bad players. I don’t make that much. Also as employees these dealers only pay half the hourly rate that the patrons pay for seat rental (seat rental is in lieu of rake).