...that is the question! Where do y'all draw the line? I know you shouldn't clean coins, but what about artifacts and relics? If you clean enough to identify/"conserve", why not go the rest of the way?
With relics, basic cleaning is the norm. Get the dirt off, preserve it and call it a day. A few will send some of their relics out for restoration, but I personally wouldn't. I prefer to leave it as it was dug, just cleaned.