Originally Posted by IcyBlueAce
Care to elaborate more?
I'm not positive about this. But basically if two players are working together, more in limit than NL, they can trap players between them. Say one bets, if a couple call, then action is on the accomplice. He raises! When action comes back to the first player he 3bets, forcing the 2 players in the middle to either call 2 bets cold or fold. Often they'll fold because these 2 should have strong hands.
In limit, if this keeps happening, then something could be up, because there usually isn't much FE, so if a guy's raising then folding, something's pretty odd to begin with. If someone asks to see his cards, and he's just playing utter trash, and it just happens to be when the same guy is betting/raising, well that'd be a good bit of circumstantial evidence, and where it leads from there I don't know.
However in NL, people make weird moves more often, as fold equity is much greater, therefore it's a lot harder to say if people are colluding in this manner, at least it seems that way to me.