This looks to me to be a situation that depends on the stakes. At 2nl, some opponents actually will pay you off w/ Qx here. At 25nl, a reasonable river bet (1/2 pot or more) likely narrows your opponent's calling/raising range to where you won't get called by worse hands often enough to make it +EV and a ridiculously small bet might induce an observant opponent to raise big w/ a missed draw.