I'm assuming you mean 'bad' in the 'loose-passive' sense of the word.
The temptation when you continually see crap hands calling down and hitting longshots in huge pots is to start playing rags yourself. If that donk at the other end of the table can get lucky, then why can't you?
It actually pays to tighten up. Expect to miss flops and have to check-fold often early in the hand, but also expect that when you hit big flops you will get paid off handsomely. You play tight because you don't want to get involved in big multi-way pots with the second or third nuts (or worse), because the chances are one of the 5 other players in the pot has you beat (while most of the others are probably happily calling with their gutshots etc). A tight hand selection means that (a) you will most likely have the best hand when entering a pot, and (b) when you hit a flop your hand will be good, as opposed to a second/third nuts trap.
Essentially, nut peddle. You can profit easily enough like this in weak games, there's no need to get fancy.