I can see your frustration. I would just say that you are inviting the bluff by checking the flop. A bet here may or may not slow them down, but by checking you are basically announcing that the flop didn't help you. Good example of how position is key. But don't feel bad; MP2 would have sucked out regardless.

if i bet the flop i have to put them on exactly the hands that they had. i have to assume they hold some premium cards, if the guy behind me re raised and he got a caller in front of me knowing i was still to act. if i wasnt getting 6:1 preflop i probably would have folded (assuming i was up against jacks at least) but i figured i would take a flop on the off chance that they had exactly what they had.

and personally, i dont like to do many "feeler" bets on a scary flop with 2 people who represented strong hands behind me. ive always though that its worth it to bluff if you can bet a little less than 50% of the pot if you think that there is at least a 50% chance your opponent is going to fold. but i dont think a bet was worth it here.

i used to misplay pocket pairs, i thought i figured out my problem: the idea is to play them strong, but based on position and such preflop, and be prepared to fold them if the flop isnt favorable.

am i wrong?

Perhaps you are looking at this the wrong way.

Did A5o have any reason to think you were passive post flop which might have encouraged him along preflop and also to interpret (correctly) that your check on the flop indicated you would fold to a bet. It's possible to interpret his play as being more about what he thought you and the other guy had than the strength of his own hand. He lucked out on the turn, but he made a good stab at taking it down on the flop.

Of coures I'm not advocating playing A5o into a reraise preflop, but if he's really good, you might have been telegraphing your play too much.

On the other hand he may just have been a loose and lucky fish.