Ok I know it's a movie but it's based on reality. The scene where the cowboy has his socks on the table and gets kicked out. Pesci really wants him in there gambling...but why?

Why does pesci have an interest in him gambling in there. What's the scam he's running?

Can't be a fixed dealer cause he's having a bad night...

Nicky (in real life, Tony "the Ant" Spilotro) was in Vegas looking out for the interests of the Mob bosses, who were skimming Ace's casino. He probably encouraged his people to do all their gambling at that casino, the better to add revenues that could be skimmed.

Don't remember from reading the book if Spilotro had a poker cheating operation going in real life, but in the movie's universe, Nicky had his crew in there playing poker and using signals to team up on other players, which is a no-no. The cowboy was obviously part of that crew but at the time he was kicked out he was probably just playing blackjack and drinking.