If I were to trust any company at all with used equipment rated 'bargain' or 'as is', it would be KEH. They have consistently shown to be very conservative with their ratings and very reliable for used equipment, and back it up with the return policy.
As it happens, I haven't bought anything worse than 'excellent', but not because of any fear of buying lower form them, just because nothing I was looking for happened to be any worse than that. The things I bought rated 'excellent' I would have labeled 'like new'.