quick question on limping in

Your in late position, no raise, you have decent cards to limp if there are enough people going for a family flop.

What is the general rule here when you can call just about anything. What pot odds are you looking for when most pocket cards can be profitable. And/or how many people do you need to limp with these kind of cards. ("these cards" being less than marginal to marginal hands that you wouldnt ness. raise.)