Villain mystery raises

[Megenoita]

Villain is 50/11 after 18 hands. I've noticed 2 guys at this table who seem to bet into the PFR or field on the flop with any piece-good piece, and no matter what the action, they bet in again on the next street. I've seen this from time to time and it's not terribly uncommon. Below is a variation of this where villain raises me every street but I don't trust that he has more than a dry ace. Here is how I decided to handle it in this particular hand. Thoughts?

Party Poker 5/10 Hold'em (6 max, 6 handed) converter

Preflop: Hero is BB with 8[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/heart.gif[/img].
UTG calls, MP calls, CO calls, <font color="#666666">2 folds</font>, Hero checks.

Flop: (4.40 SB) 4[img]/images/graemlins/heart.gif[/img], A[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets</font>, UTG calls, MP folds, <font color="#CC3333">CO raises</font>, Hero calls, UTG calls.

Turn: (5.20 BB) 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets</font>, UTG folds, <font color="#CC3333">CO raises</font>, Hero calls.

River: (9.20 BB) 7[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, CO calls.

Final Pot: 11.20 BB

I didn't 3-bet the turn because I didn't feel like calling down a cap, but then on the river I thought that it would suck if he's being a donk and I don't get another BB in, so I decided to bet/call the river.