[phish]

[ QUOTE ]
Hi Stox:

Your answer is incorrect. The correct answer has to do with exactly how often he might be out of line and will then bluff the river after your fourth street check. With some players, their chance of being out of line on the flop is quite high, and then their chance of bluffing the river is also quite high. With this type of opponent, it's clearly correct to check the turn.

By the way, many of these real aggressive types, if they held a real hand, will always go for a check raise on fourth street after you raise on the flop. That's part of the reason why your answer is not correct. Their three betting the flop actully means less strebgth, not more.

Best wishes,
Mason

[/ QUOTE ]

While I would generally agree w/ Paluka and Bicyclekick's line in situations like this, there is also much merit to Mason's (and other's) take also. And one thing that no one has mentioned is that, in addition to possibly inducing a bluff, you may get paid off by AK AQ 44 33 or other hands that you beat.
Think of it like this: after the flop there is 7.5 BB. Add a bet and call on the river and the pot is 9.5 BBs in total. Now if your opponent actually has a hand like 44 or AQ and may fold the turn, this would be bad for you if he's the type who would call a river bet.
With AQ, he only has 3 outs, which is has 3/44 chance of getting there. So, if he would've folded the turn, but would've paid off the river (assuming you'd bet the river if he checked, which you should) or bet the hand himself, his call on the river gives you a greater expectation than your giving him a free card on the turn gives him.
(This, of course assumes that he would be very unlikely to fold a hand stronger than yours on the turn, which is a reasonable assumption as someone else has pointed out.) Also assumes he would not have played like this with a hand like KQ.