As ghosts they're always in search for a target and don't especially care who it is. If it's not Springtrap, it's the employees of the fright. Although they can't hurt anyone, they can cause people to hurt themselves.

They're always present, whether you can see them or not. It's easy tell when one is around because it'll suddenly start to smell like smoke.

I sure hope you didn’t take any drugs before this shift buddy!