Yeah only time I raise them is to isolate limper fish or TAG
When I open with them its to steal, I really don't want a caller in position to me (although I do open it sometimes from MP or CO for balancing in SH), and I don't want a 3-bet.
Its also effective as re-steal hands from SB or BB.
But all of this really depends on opponent. If he only raises my blinds rarerly I fold them, if he does it a lot I 3-bet higher ones.
Of course getting called and hitting a major pot with them is really nice because they can hardly ever put you on it (I mean who the hell 3-bets 78s from the bb
)
Oh and advanced (never did it because occasion is so rare and its very borderline):
MP or UTG limps and he is doing it more then once. BU or CO is a good TAG player and isolates. You have suited connectors in the BB... good 3-bet chance here to steal the pot. Your acting as if your having JJ+ AQ+ in the eyes of the TAG and his range is much worse then this since he knows that MP or UTG is a fish who limps a lot with very marginal hands (like suited connectors etc. haha). See the irony of the play?
But yeah very risky.