in games where people will call with anything

1) tighten up bluffs - i.e. dont do them

2) loosen up on legitimate hands - i.e. if you think someone will be making huge bets with any pair then be MUCH more likely to call with only bottom 2 pair.
If you think someone will call with anything then any hand that can beat a pair. If you think they will call with nothing then bet high pairs.
you dont need to know if they have anything as long as you dont go all in when you have a good (but not great) hand like top pair.

e.g. If you make bets and are called all the way to the river and then they turn over their cards, the only thing that matters is that up to the point when they turn over their cards there is more than a 50% chance that you have the winning hand.
If they call enough with losing hands then it doesnt matter if they occasionally call with winning hands and you lose.
You will WIN in the long run.
I think the most important thing to remember for this type of game is to not assume that they do not have a monster just because they are worse players than you. Dont go for crazy all-ins unless you are almost certain you have the best hand. Play very tight and when you do get good hand (e.g. Trips on an unsuited, unconnected flop, Ace-high flush, nut straight etc) then bet ALOT and be called by top pair etc