There are a few security things to be aware of which should protect you from the scaremongering. Obviously don't add anyone you don't know, but also check your security settings. Often profiles are visible to anyone in the same network by default (this is where the tales of people being sacked/refused a job after photos were seen by the boss come from), so turn that off. You don't want a public search listing either. Apart from that, the obvious stuff applies like blocking out registration numbers in photos (if you post them to a group, anyone can see them).
You should be safe enough after that - I've not had any spam from random users. Mind you, I suspect it might be rather different were I attractive and/or female!