Totally agree, but remember they're just consignment sellers who take a 25% cut. Their prices likely reflect the optimism of their previous owners, coupled with their knowledge that they're only getting 75% of asking.
So the prices are usually inflated, but every once in a while there's a fair price on something unusual. And they absolutely do a lousy job really inspecting the knives closely, and I've told them as much. I've also learned that they realize they don't do a great job on that front, so if you find a detent or centering that isn't "nice" (as they invariably describe them), they'll take it back no hassle and no fees. That is to say, their return policy is generously flexible, because they know they're not keeping up with the volume of what they're handling. (They do about $9m in sales annually, I hear!)
But that's mostly academic, because you're right...they can't really be relied upon, so I tend to avoid them unless I get an alert that something has been listed that I can't live without.