TPTK paired board, horrible opponent

I have opponent covered. He is horrible, very loose, pretty aggressive. Saw him go all in with top pair no kicker. Normally I'd just let him bluff but I think he'd call here with a weak pocket pair or may be even ace high vs a turn raise. Should I be betting this river? What if I think he has total crap most of the time?

Party Poker No-Limit Hold'em (NL$200) <font color="#0000FF">(6 handed)</font> link

Preflop: Hero is UTG with A[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/spade.gif[/img].
<font color="#CC3333">Hero raises to $6.00</font>, <font color="#666666">3 folds</font>, BB calls $4.00.

Flop: ($13.00) 3[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $2.00</font>, Hero calls $2.00.

Turn: ($17.00) 6[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $8.00</font>, <font color="#CC3333">Hero raises to $25.00</font>, BB calls $17.00.

River: ($67.00) 3[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks