Agreed, bet, bet, bet/fold. No one really bluff raises river at low limits. However, it's not a snap fold. All we do know is that Vil is polarized. We also know that river raises tend to be skewed to the nuts at the lower limits. Time to hit the tank (what do you have? 60sec in Cherokee?)
Value hands that raise the river:
*77, 66 33, 22. Think we would have heard from a set sooner.
*65cc, 64cc, A6cc. Do we think he calls pre with 64cc? Probably not, so 65cc or A6cc are possible trip options; any other 6x combo SHOULD fold turn.
*54s - doesn't seem very likely; again wouldn't we have heard from this holding sooner?
Bluffs that raise river:
*89cc, 89 (OESD)
*T9cc (gutshot + 2 overs, + turned FD)
*A5cc, A4cc (gutshot + over, + turned FD)
*A3cc (bottom pair + backdoor + over, + turned FD)
*Lite floats that turn backdoor clubs
Keeping in mind everything I just listed above is my best effort to cast a wide net of holdings and work backwards. When you revisit the HH, the only value hands I see him with here are A6cc or 65cc. That's 2 possible combos of value hands. Looking at bluffs, 89cc is a must, but I think 89s gets there often enough, so that's 4 combos of 89s. I wouldn't throw out the baby suited aces, there are 3 of those, even if we take out 50% of those, that's another 1.5 combos of bluff raises. T9cc is a little more generous but still possible. And you can ignore floats that turn backdoor clubs, and we still have 2 value combos v. 4-8 bluff combos (8 if we count all 4 89s, 3 AXcc and T9cc; I just halved the frequency for the bottom end estimation). So on the low end we have 2value:4bluff, 1value:2bluff - we expect to be good 2 out of 3 times; on the high end 2value:8bluff, 1value:4bluff - we expect to be good 4 out of 5 times.
Pot is $870, it costs us $230 to call. We only need to win 1 in ~4 to break even. Do I think we win more than 1 in 4 times? Combinatorially, yes.
As a final note, while river bluff raises are rare at low limits, spazz bluffing to represent trips is one of the more common bluffs people attempt. Here it just doesn't make sense. So while my first instinct facing a river raise would be to muck, I would also note how little sense this line makes. When you review the HH, I think we find that while our Vil is polarized his likely range is skewed towards air.
**Okay yes, I realize A3cc has SD value and we expect he does not turn this into a bluff, but isn't it possible he recognizes that bottom pair is never good here and turns it into a bluff instead of hero calling and hoping you have 3 barreled with AKhi?