I only play limit - so this might sound like a dumb question. But don't you have to think about the turn bet as well? OK you get just about the right odds on the flop for the flush draw to come in by the river, but if villain puts another pot size bet in on the turn what do you do? There's only one card to come so you are worse than 4:1, but you are still only getting 2:1 to call.