BB was high vpip loose passive type. No reads on SB.
I open BU and both blinds call. Flop gives us dry mid set. If I had like AT22 I would check without fd. Should we do same with mid set? As played I really dont like the spot but can we fold either?
As SB is unknown, it wouldn't take too much effort to think non-JJ hands that would raise the flop. I wouldn't fold a middle set without reads.
This was quite a spot as it was set over set over set. SB had JJ, BB 22. I shoved flop and managed to hit backdoor straight so quite a luck box 
If flop was J♦:7♠:2♠: I would not really think of folding as flush draw combos would be way more likely. But on this flop its probably close.
Not folding here either at ~120bb without reads. But since I usually have reads I am still folding quite often. Never underestimate the nittiness of nits.
I see no problem in checking back mid-set sometimes for balance, I would take the very weak ones like the one u had: no fd-blocker, no bdfd, no gutshot, no pair, basically nothing. You are supposed to check-back quite some of your midsets in 3way ip spots afaik.
This was quite a spot as it was set over set over set.
That does not tell much imo, no matter what player type... nobody is supposedly or perceivingly folding topset here...^^
