I'll also add that I've had good and bad luck with KEH. Most people will recount that their BGN grade purchase was in near perfect condition, and I've had similar experiences sometimes. But they have to do that because you don't get to see what you're buying. So you feel your bargain item seems excellent you'll dismiss the light cleaning scratches on the rear element. But if they had called it excellent, you would be far more picky.
It doesn't always work that way. I ordered an excellent Gitzo tripod, when it arrived I'd have listed it as ugly. It had peeling stickers, was missing one of the rubber grips to turn a leg lock, and jut looked heavily worn. Unfortunately I ordered it a week before a trip so when it arrived it didn't have time to complain or return it, so I ended keeping it.