Since I've started playing the $200 on UB, I've notices a considerable difference in how flops with three to a suit are being treated. Some examples:

1) Flop is 26A clubs, I have the K of clubs in the SB. Checked to button, who bets pot. Since he often bets in LP to steal, I raise pot ($40). To my dismal, the BB cold calls, and the button moves in (he has $120 behind) with the second flush. I fold of course, and BB calls allin with middle set.

2) Flop is 37A spades, I have AKsJ5s and bet pot ($20). One caller, who has $50 behind, so $30 after my call. Turn is another A. I push in the remaining $20 and he calls. I don't fill up, and lose to 77.

3) Flop 67K clubs, I have nut flush. MP bets $10, LP (who was the button in hand 1) calls, I raise pot, LP calls for 2/3 of his stack. Turn pairs the board, and again there is too much money in the pot to give up.

Obviously these calls are all very wrong from a purely mathematical point of view. The only reason I can think of is that at this level, if someone who bets a flush board it is relatively often the case that he is bluffing, so that a set or small flush is ahead often enough to make such calls +EV.

How should I respond to these plays, apart from not bluffing of course? Against a deep stack it is easier to get away once the board pairs, but the scenarios in hands 2 and 3 are fairly typical, in that most of the money goes in before the board pairs, and then once the board pairs you face a $40 decision in a $180 pot. I'm afraid that if I start folding those, it will invite bluffs. On the other hand, all these hands start adding up to quite a large sum of money, and even with a decent winrate at this level, it is too much to compensate for.

Any thoughts? Is this the same phenomenon as the fact that in higher games middle set is going to be played as top set?

Pieter