I think KEH went through a rough period when they were sold, people left, and new people were hired. Since then, they have improved.
Generally I’ve had good luck - I always buy EX or better. One disappointment, which they can’t really be blamed for not noticing, was a camera which appeared pristine but the frame counter wouldn’t go much beyond 24. Another was a rangefinder with a slight upward bend and separation in the top plate assembly - visible once it’s pointed out, but a neophyte wouldn’t notice it.
The only bad experience was a “like new” rated item which was not only beyond ugly when it arrived, it didn’t work either. It looked like someone had dragged it along a gravel road for a few miles. Even so, I would’ve kept it had it worked. I called KEH, described the problem, sent photos of it (with serial number), plus the plastic KEH bag (with serial number and “like new” rating. The accepted it back, refunded me, and I was told they had a meeting inside KEH to discuss and correct how this happened. So - much credit to them for handling this the proper way. In my long experience employed with high-tech companies making consumer products, problems are always going to occur - it’s how you handle it and help the customer that counts. So KEH does it right.
My last item, a few months ago, was rated EX+ and when I received it, it was like new - like it had never been used. So I was happy to get that and it reinforces the notion they grade conservatively.