One thing I've been wondering about in fixed limit 5CD is also this: suppose one player open-raises the pot from the hijack, a second one calls cold from the cutoff, the BTN folds and you're next to act. Assume this is a new or unknown player and you don't have any notes or reads on him yet.
What would be your minimal playable hand at this point? Do you consider this situation similar to playing after a raise and 3-bet on the predraw round, despite the fact that the 2nd player merely called the raise cold, and as such did not really show any strength?
Of course it's possible that this is a weak player who simply never 3-bets but simply calls when he finds a playable hand after a raise, but I think there aren't many players like those: even players who limp in the pot being first-in tend to fold after a raise nowadays