I do think that KEH gives a once over when a camera comes in to check its functionality, either its working or its not. How well might depend on the person who is actually doing the examination. Doesn't KEH grade items based on physical appearance when compared to when new?
It's sometimes the luck of the draw, but the one thing about KEH is they do make good on their part. You have the option of asking for a replacement, repair, or refund. At worse if you don't like it you can always send it back. Sometimes they only have one item in stock so if you don't like it your pretty much out of luck. Inconvenient and annoying but at the end of the day you still get the money you paid into it back. (minus the shipping, ups makes a buck out that..)