Personally, I would never, ever rent out my gear to strangers.
There is just too much room for ‘things’ to happen. And when (not if, but WHEN) they do… you’ll have quite a headache on your hands. First it will be difficult to get all but the most honest, ethical people to admit that they damaged your gear.
Then, once (and IF) they do cop to it… how will they pay up? Do they have the money? How much? You’ll want to be ‘made whole’ – get the damage repaired PLUS it is not unreasonable to expect compensation for the downtime that your camera is not available for work. The other party, of course, will very likely not agree to this unless – again – they are highly, highly ethical and fair-minded. And loaded with cash.
I would only consider renting my gear to people whom I know and trust. And even then… I might insist on being on location. I baby my gear; I would expect anyone else who uses it, to treat it as if it were their own.
I could excuse a bit of scuffing on the body that wasn’t there before. But the chief concern is the lens. My camera’s lens has NO scratches on it, none. It is immaculate. Suppose your camera comes back with a slight scratch on the lens. Imagine the arguing that would spring from that. You’ll want the lens replaced. They’ll say it was already there and besides, nobody will notice it. Unless, again, you are dealing with that mythical being, the 100% honest and 100% ethical person.
You know how people treat rental cars? Well, there you go…