well he was either a really bad player or a really good player. Really bad in that he called a raise with A6 and called an all in with 2nd pair but if he was really good he probably put you on a steal and figured his pair was good. Good players tend to see a strong bet on the flop as a sign of bluffing (especially on the that flop, there was no reason to reraise strongly if you had anything since there are no apparent draws) and will even call with Ace high. If you had a strong hand like 2 pairs or a set you would most likely flat call and hope he bets again on the turn. Bluffing with rags is a good strategy to steal blinds but if you get called, you really shouldn't continue with the bluff unless you have a really good read on your opponent.