Value bet overpair on river with str and flush on board?

[vabogee]

I'm trying to improve my river play lately, and I'm finding this situation a lot in games where everyone's calling down. I also find that many players will either wait in the weeds with a better hand or just call down with a better hand.

SB is insanely loose and passive, BB is TP, and MP is another calling station.

Party Poker 1/2 Hold'em (6 max, 6 handed) FTR converter on zerodivide.cx

Preflop: Hero is MP with K[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/diamond.gif[/img].
<font color="#CC3333">UTG raises</font>, <font color="#CC3333">Hero 3-bets</font>, CO calls, <font color="#666666">2 folds</font>, BB calls, UTG calls.

Flop: (12.50 SB) 9[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, CO calls, BB calls, UTG calls.

Turn: (8.25 BB) Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
BB checks, UTG checks, <font color="#CC3333">Hero bets</font>, CO calls $0.24 (All-In), BB calls, UTG calls.

River: (11.37 BB) 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players, 1 all-in)</font>

bet? or be safe?