Spoon is right. You can, of course, get away with open limping in a very narrow circumstance, which is where you can read the table and are confident that nobody's going to raise a limped pot except in very narrow circumstances where you would want to get out anyway. And advanced players can limp re-raise in certain circumstances (basically when you have a strong hand you want heads-up and are confident that your limp will be iso-raised by a player acting after you whose raising range is way behind your hand).

But those two scenarios comprise probably 1/10 of 1 percent of all the poker you play. Which means that open limping should be about as rare in your game as hitting quads.

In fact, that's probably a good measure of how often you should open-limp. If you open-limp more often than you hit quads, you are doing it too much.