Ahead here?

Should i bet here or check it down? Why?

***** Hand History for Game 2333970949 *****
$200 NL Hold'em - Saturday, July 09, 02:18:42 EDT 2005
Table Table 55281 (6 max) (No DP) (Real Money)
Seat 2 is the button
Total number of players : 6
Seat 1: bigbadbennyb ( $303 )
Seat 2: Pennypacker_ ( $196.7 )
Seat 3: WHITEBLACK ( $424.31 )
Seat 4: EvilEcstasy_ ( $100 )
Seat 5: FTPickle ( $186.55 )
Seat 6: ish42tc ( $465.41 )
WHITEBLACK posts small blind [$1].
EvilEcstasy_ posts big blind [$2].
** Dealing down cards **
Dealt to EvilEcstasy_ [ Kd Kh ]
FTPickle folds.
bigbadbennyb folds.
Pennypacker_ folds.
WHITEBLACK calls [$1].
EvilEcstasy_ raises [$3].
WHITEBLACK calls [$3].
** Dealing Flop ** [ 8d, 4s, 5d ]
WHITEBLACK checks.
EvilEcstasy_ bets [$7].
WHITEBLACK calls [$7].
** Dealing Turn ** [ Jc ]
WHITEBLACK checks.
EvilEcstasy_ bets [$20].
WHITEBLACK calls [$20].
** Dealing River ** [ 7s ]
WHITEBLACK checks.
EvilEcstasy_ ???

Check behind. Only better hands call or raise. Looks like he was on a pretty clear flush or straight draw. The latter hit on the river, and he would be looking for a big checkraise there (betting out would be a little obvious with 4 to the straight on board). You can't think he had a set because he didn't raise anywhere to protect against the draws, but if he did rope-a-dope you with a set, he will also probably check-raise you on the river.

What do you think he'd have that you beat that he would call a river bet with? Only possible hands would be QQ or 1010, but either of those I feel would've raised you on the flop when they flopped unders with a lot of draws. Do you really think you're going to get calls from hands like A8 here? AJ, if he made a loose call on the flop, would be the only hand I could see calling a reasonable-sized bet here that you have beat. Otherwise, most of his probable holdings will fold to any sized bet, making it more risk for very little extra money in the pot.

Chris Ferguson has an article about this somewhere -- how betting medium-strength hands on the river when only better hands call/raise and worse hands fold is a bad move. Granted, he was talking about limit, but the same principle applies. Result?

EvilEcstasy_ bets [$40].
WHITEBLACK calls [$40].
EvilEcstasy_ shows [ Kd, Kh ] a pair of kings.
WHITEBLACK doesn't show [ Js, Th ] a pair of jacks.
EvilEcstasy_ wins $142 from the main pot with a pair of kings.

I figured an open-ended straight draw would actually NOT have caught here (unless it was a gutshot, doubt he would call with that), though it was likely he had picked up a pair a long the way. I figured he didnt have two pair or he would have bet or raised on flop and turn. So I bet a sizable amount, and was called by someone who had picked up a jack on the turn.

this is the type of situation where sometimes you bet it and you get called and win, but sometimes you bet it and get raised and have to fold. in 6max, i think betting a river with a medium hand is ok as long as you're willing to bet it solidly.

I usually check behind here as well, but maybe I give my callingass opponents too much credit. This was a horrible call by the guy. I'll be he was crossing his fingers that you were a whiffed AK bluffing the straight draw. I have to think that usually this is a bad bet because usually he's only calling with a better hand. In his place I check/call that river with a set and a 6 only.

Whats up with your preflop raise?
Whats up with his flop call??