In reply to cragtyke:
I've never heard this, although my cams have slings which I clip either with a draw or just the racking krab depending on whether it needs to be extended etc.
What would be the alternative, if your cams didn't have slings? Clip the rope straight to the wire on the cam? Seems like a guaranteed way to make your cam walk...
Where did you see this advice, just out of curiosity?