Is it best to just c/f flops vs. aggros on bad boards as the PFR when OOP?

It seems like your question focuses on only one of several potential outcomes. Sometimes they slow down rather than barreling. Sometimes we improve. Sometimes we catch them bluffing.

It also seems to treat all your opponents the same. Some are more passive. Some more aggro. Some will under-barrel.

It also ignores the scenarios in which you raise with something worse than TT+ and smash the flop.

Not with an overpair. Sometimes with 2 overs.

Think about what your entire range wants to do. If you don't like how your range is interacting with low-low-low perhaps its time to add more 55, A5s, and 45s to your EP opening range. It's like me when I complain that I raised KQo pre IP and some guy just flatted out of the SB with AQs and the runout comes Q-blank-blank-blank-blank and I lose a large pot betting into a better hand. I have to always keep in mind that V's play their value so passively that I'm often behind in these spots, I often flop the second best hand, then decide if I need/can start bluffing or if it's a give up or what.

In your example some relevant tendencies live are: people massively under barrel, people massively under bluff, people massively overstab when checked to, size with the absolute strength of their hand.

So the adjustment on low-low-low (if I were to be a nit from EP which I'm not): check/call my entire range OTF FOR VALUE, check/give up my A-high/K-high OTT, check/give up my weaker pairs OTR, ...all while evaluating sizing for signs of strength/weakness.

Getting out early is a superpower.
I think you’re kinda talking fit or fold.
It’s definitely a topic worth discussion, but I don’t know if there are any easy answers.

A lot of times floating the flop is a strong play. Sometimes villain quits on the turn
They usually figure you’ve got something
Villain could check and give you a free card
You could hit your hand on the turn

You have to look ahead
Maybe villain is going to charge you for tagging along and you tighten your continuing range. Maybe it’s all feel and reads

The rake pushes tighter than solver play. If you’re not sure whether it’s a fold, it probably is. You look for favorable situations and to avoid reverse implied odds.

My guess is that you have good instincts. If you decide to fold, the outcome doesn’t matter. I think that when you decide to fold a strong hand, you’re often happy you did.

“Fold, and live to fold again.” -Stu

I think there’s a danger of over adjusting to aggro players here and ending up massively overfolding.

If we start folding overpairs too aggressively on low connected boards, we basically allow aggressive opponents to print EV with stabs and barrels.

Using your example, UTG opens 8-handed, aggro BTN flats, everyone else folds. BTN’s flatting range is somewhat capped because an aggro player is probably 3-betting a lot of premiums already. So we’re looking at something like 22-88, suited broadways, some offsuit broadways, SCs, and Axs.

On 864r, this is definitely better for BTN than for UTG in terms of nutted hands because BTN retains all the sets and more straight connecting combos (pair plus draw, OESD etc.). But BTN still arrives with a lot of air and marginal holdings too. He only has 9 set combos.

UTG still has the overpair advantage and likely retains overall equity edge despite lacking the nut advantage. Because of that, I don’t think we can fold AA-TT to a single 1/2 pot stab after checking range. That feels far too exploitable against an aggro player who is likely over-stabbing these spots.

I actually like a lot of flop xc AA-TT here. Although I am not personally checking range, I can understand that line. Calling also keeps villain bluffing instead of forcing them to play perfectly versus a check-raise.

From there, runouts matter a ton. Overcards and board pairs are generally better for UTG. 4-liners are much worse.
River decisions should depend heavily on sizing and runout texture.

Q turn and T river feels like a much more reasonable fold facing large river aggression because villain is barreling cards that interact well with our perceived range.

Cleaner runouts like 4 turn and T river, I think bluff catching becomes much more mandatory.

I completely agree that we shouldn’t stack off overpairs too liberally in these formations. But if aggressive players can barrel us off AA-TT with impunity every time we check low boards, that becomes a major leak too.

HU or multiway are different.

Multiway a bunch of the other randoms will be protecting you on 864 when you open EP.

HU you are allowed to x/r flop bets, and it doesn't need to be huge, because in general x/c isn't enough of an opposing force.

Banana's point of having more board coverage can help sometimes, but it's difficult to do well (and not be just spew opening CO ranges from UTG). Esp. so when you are doing it to counter a CO/BTN and there's 5+ average 1-2 calling stations between you.

864 isn't that bad either, lots of players will happily bet any 8x and even 76/65/77/55 without thinking about anything else. Agros. might bet any pair 7 or 5, which is even better for you x/r'ing. Also without a flush draw you don't have there aren't that many bad turn cards.

As others said you can sometimes know when you want to x/c or x/f given the bet size they chose.

The people being "agro" at 1-2/1-3 esp. don't have good strategies/theory, they have a bunch of patterns they know like "V opens and checks flop, means they missed" or "V opens EP and board is 8 high, means I can bluff a lot" ... so anything that you do which breaks/changes those patterns will be very helpful.

But, yeh, position is a thing ... I will often just sigh x/f AK on 864 even if it's the best hand a bunch.

Fish can run good too.