It's also worth noting that the higher his bluffing frequency gets to approach that 30% benchmark, the lower the difference in expectation between a call and a fold. So if you are right, and his bluffing frequency is close to 30%, EV is going to be mostly identical anyway.

The only time folding becomes lower EV is when his bluffing frequency gets noticeably over 30%. Unlikely though, it would be a bad assumption to make about an unknown.

Im totally with you that ppl are underbluffing heavily on these limits. The big sample you have drawn conclusions of is a good guide line. But this spot is so far from standard as I tried to explain in the last post.

The board is doubled flushed and bricks. Every hand he opens is a potential good 2 barreling hand when the turn favours the CO opening range. We are capped here when we dont raise the turn, he is not. When we get to the river we are close to top of our range.

If you compare this to another spot that would be in your sample:

SB open BB calls. Flop K82r turn 2r river 3. This is very likely to be a spot where they 3 barrel bluff close to 0%.

I think you should take the hand as it is. In a vacum this is a must call. I would for sure use your info in tougher and closer spots and would lean towards folding if the decision is close.

what good nl100 reg is openin 3x CO?

good point but on that board there's a lot fewer 3 barrel value hands say AK, 88, 22 (16 combo's).
Compared to our board where he'll 3 barrel AA,KK, QQ, JJ, 44, 55, 99 and Qx with a good heart or diamond draw (40ish combo's)

So although we have more potential bluffing combo's on this board we also have more value too.

We've sort of looked at the two extreme's (dry boards and v.wet boards that bricked). If we take a more average board, say KhTh5d 2s 8c.

Now we have value KK,TT,AA, 55, KT, AK, (36 combo's)
Potential bluffs QJ, and hearts (37 combo's)

Weazel stats show over a large sample that only 16% of triple barrels are bluffs. So this should be roughly true on an average board. So given he has 36 value combo;s and 37 potential bluffs the average player is only bluffing around 1/3 of them.

And on our actual board I estimate we have 50 bluffing combo's so the average player on our board is still only bluffing 16 combo's. So he would have a bluffing rate of 29%. Which is below the threshold, so the EV between the two options is probably pretty similar. But even if it was slightly more EV for such little EV it's probably not worth taking on the variance.

Of course though there is the argument a slightly -EV call to see your opponents hand can be long-term +EV if we learn something from what he showsdown. So I don't mind a call or a fold now tbh.

Just something to add to this, because I think it is something that will affect villain's bluffing frequency enough to make it a fold, is that the 4 pairs OTR. Sure he has 2 less 44 combos, but people tend to bluff les on paired rivers as they assume they get called down more. Typically if a board pairs OTT or OTR people betting = value a higher % of the time.

I don't think calling would be bad, probably around break even against the population given the draws missing, it is of course possible that villain is over bluffing in this spot. But it is going to fall between a small mistake and a very small +EV play to call so folding probably is the best play. Agree that from a GTO standpoint it is a call, and on this texture is correct, but in play folding is probably better.

good point, I think people don't bluff rivs that pair much.