Overall I have had good experience with KEH over the years. Almost always, their cosmetic rating is conservative. But several items I have bought have definitely been in need of a CLA, or immediate replacement of mirror foam. I have concluded that is fine with me—as I have come to factor in a CLA, and feel that a fine camera deserves it.
In my experience, the salesman will not preview the equipment before sending it out. If there is a disagreement over cosmetic condition, the buyer gets a hassle free, prompt refund, despite the fact that their website warns of refunds taking up to two billing cycles. The price to inspect the equipment is postage two ways. If there is an undisclosed clear mechanical problem, they will take the item back and pay the postage.
But once I ordered an OM-1n in EX or EX+ condition from them. It was a beauty, but upon the first firing the mirror stuck to the foam cushion, which was gummy. KEH gladly took the camera back, did not offer to simply replace the foam, and I paid postage.
With tempered expectations in mind, I view KEH as a good value for the buyer. I have never been tempted by their offers to sell to them, however.