I know you should never open limp.. but when you find yourself at a loose passive table, that doesn't really apply. If you limp, chances are good that you'll see a flop, because most of them raise only AA/KK, maybe QQ/AK. And if you have say 78s, it's stupid to raise it.. you'll just end up being called and not having an edge.

So on tables like that, open limping is fine imho.