Experience purchasing a used high-end cartridge

Having quite a few used cartridge purchases under my belt, I will chime in. I’ve only had one issue buying a used cartridge. It was an Ortofon Bronze that had a bad channel. Can’t remember if it was left or right. One side ohmed out properly. The other was open. The stylus looked great yet the cartridge itself was junk. Other than that. All other purchases were as described. 
 

Go with your gut feeling. If something seems off about the seller, walk. 
 

Run. 
 

Plenty of other people selling used cartridges that are above the board. 

I have bought and sold many used cartridges over the years. I agree with one of the poster that talked about getting it inspected.  I personally have never done that and have knock on wood not been screwed out of my funds.  Good luck with you cartridge purchase whether its new or used.

Thank you all for the well-considered advice. @neonknight I greatly appreciate your engaging narrative and wise advice. My takeaway from @wrm57 and many of the others is to assume a steep risk curve if seller reputation involves any ambiguity--as is the case here.

@lewm, I resonated fully with your remarks which I find equally edifying to those I’ve read when lurking on other threads. @ghdprentice, same for your comments -- fortunately for me, my teenage purchase of a four-year-old ’72 Olds Cutlass bought me many years of cruising (parking) fun--though I admit to only buying new cars ever since, hence my reticence about the used cart.

Daring to synthesize the remarks, the risk-benefit tradeoff shifts towards benefit if independent, highly-reputable inspection can be obtained before purchase. I will give that a go. If the seller refuses, as @lewm stated, I will have my answer.

I have purchased many MC carts used through the years. 
I have never been disappointed. I once purchased an AT-ART 9xA for $650

Seller put clock time on every cart. His feedback was tremendous. I was very satisfied. I have purchase a few more carts. 
Huge upgrade. 

I have used the Condition Check request for Valve Purchases.

I negotiate as part of the sale, the Valves are to be tested when I receive them, and are then kept on returned dependent on the measurements taken.

If the Vendors measurements are close to ones taken on my behalf, I have honoured the Purchase, in some cases the measurements on my behalf have been much improved over the Vendors recorded values.  

Having a assessment agreed as part if a sale agreement is one more step towards Caveat Emptor.