25NL - bluffing TAG on a scare river card

[fievel]

Villain is 19/8/1.8 after 90+ hands.

Party Poker - No Limit Hold'em Cash Game - $0.10/$0.25 Blinds - 4 Players - (LegoPoker Hand History Converter)

SB: $29.81
BB: $21.48
UTG: $25.00
Hero (BTN): $24.98

Preflop: Hero is dealt 6[img]/images/graemlins/heart.gif[/img] 6[img]/images/graemlins/diamond.gif[/img] (4 Players)
UTG folds, <font color="red">Hero raises to $1.00</font>, SB calls $0.90, BB folds

Flop: ($2.25) 2[img]/images/graemlins/spade.gif[/img] 9[img]/images/graemlins/club.gif[/img] 4[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">SB bets $2.00</font>, <font color="red">Hero raises to $6.00</font>, SB calls $4.00

Turn: ($14.25) A[img]/images/graemlins/spade.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $8.00</font>

His rather big donk bet looked like a pot stealing attempt, I don't think he would do it with a flush draw.

Any comments?