Okay, I'm going to make this clear.
Having survivors on your team is good...but you need to trust them. To make sure they understand that, if you are bitten either get them to shoot you, if they won't, do it yourself, or cause a distraction to the zombies close by.
The reason to trust people is so, they don't just kill you in your sleep and take your weapons or anything else that is useful to you. It would be a mistake to have it in wrong hands.
Respect is another thing, if you show respect to them, they should do the same back, if they don't...you might have a problem on your hands. Or, they have just been driven crazy that such thing like zombies exist.
Crazy people are not the type to make alies with, they can cause a lot of arguments with you or other members on your team. They may also have the idea that you might want to kill them, they are most likely hostile.
Just some tips on people you should trust.