Rivered straight on paired board

[SkittleBrau]

Party Poker 3/6 Hold'em (6 max, 6 handed) converter

All villians are very loose and passive. 50-70/0-10. AF <1

Preflop: Hero is SB with 6[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, MP calls, CO calls, Button calls, Hero completes, BB checks.

Flop: (5 SB) 5[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(5 players)</font>
Hero checks, BB checks, MP checks, CO checks, Button checks.

Turn: (2.50 BB) 3[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(5 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">BB raises</font>, MP folds, CO calls, Button calls, Hero calls.
I picked up two draws -- still too weak to try to semi-bluff all these loose players?

River: (10.50 BB) 7[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
Hero checks, <font color="#CC3333">BB bets</font>, CO calls, Button folds, <font color="#CC3333">Hero raises</font>, <font color="#CC3333">BB 3-bets</font>, CO calls, Hero calls.
When passive BB 3 bets, I'm afraid he filled up (or, rarely, CO going for overcalls). Too weak?

Final Pot: 19.50 BB