The thing is, you need your opponent to be strong in order to draw to a gut shot profitably.

If all they have is a foldable pair or they are c-beting, you can't really get any implied odds. You need a solid read that you can hit your gutshot and they will seriously think about calling a big bet. It's best, of course, when they have a habit of under-betting a monster (2p or a set) so when you see small bets, you have better odds and they are more likely to pay you off.

I think if you're calling with a gut shot because you think your opponent is weak, you're making a mistake. You might not beat a bluff!