I also think - this occurred to me right as the film opens and we see a closeup of a glass of whiskey as Eddie talks to Helen a Shaver and says something about the color of the knockoff bourbon he sells - that Scorsese and Price were making a minor point about this sequel being shot in color, while the Hustler was black and white, which was a conscious choice made by Robert Rossen at the time.
I wanna find one face that ain't lookin' though me
I wanna spit in the face of theseBadlands

Also, I have thought that it might be a comment on Vincent being green and inexperienced (a newbie or n00b as a fresh person is called online).

Seriously, what is your deal with women? Have you never seen a couple hang out together? Have you ever been to a pool hall? Or anywhere? Do you have anxiety attacks when you see a chick on the back of a chopper?

The pool tables are green, like money. That is the only connection i can see. It was ok movie but Vincent is annoying - his jokes make no sense like about the "guy in the bible with the many colored coat." I found The Hustler just as flawed because of the female relationship. It is hollow like Carmen in TCoM. Why does she enjoy sitting in a bar watching Vince play pool and holding his money, taking off his jacket, watching him play Stocker video game, and so on? She could do a lot better. Until Eddie came along, Vince was just a small time loser who couldn't even find a decent opponent to hustle.

The title came from the book.