In a literal sense, it's "tested"; like, "this has been turned on, ever". It definitely doesn't mean it's been thoroughly checked out, and there are no details provided. I've had my handful of cabinets delivered from KC, with good and bad. I know what to expect, and I'm not defending his practices. The point here is that nobody in the world expects that it comes with the test board, and virtually every seller does it.
I have held up a blacklight to a monitor, and pointed out some minor burn; he didn't miss a beat, and insisted "no burn, no burn" while I'm pointing at the burn. I got a Blast with an absolutely fucked monitor and a cracked body, and pointed at them, being told we'll "deal with it later" (it was not resolved).
This goes both ways, though. I got a cheap Astro because "the monitor doesn't turn on", and then on the way I got a call, where he told me "actually, the cabinet has no power supply. maybe the monitor works". Inside that cab, I found the power supply... tucked away in the corner, unplugged. I plugged it in and it worked, so ???
Things like a structurally compromised cabinet, or an unfixably damaged tube are over the line for me, but things like a joystick being broken, or a button being stuck, or a wiring harness having a snapped off ground, or a CCFL lamp not being out are fair game for me. From an importer, I don't think anybody should purchase anything and expect a 100% good-to-go cabinet that's been gone over twice with a fine comb. If you aren't prepared to work with these kind of things, either pay a lot more and buy from a private owner who has worked on the machine thoroughly, or choose another hobby.
However, I do not think any of these things validate his janky business practices.
The (relatively low) expectations I laid out above are ones that I developed through second hand accounts, and later my own experiences. It would be preferable, and less janky, if these kinds of expectations were laid out by K C himself, as a policy. It's totally okay to sell cabs cheaper, with a lot less guarantees attached to them, but it should be laid out clearly from the start, and not used as a rationale for a cheap price or as a weapon in the game of buyer's remorse.