Do you buy used carts/needles? Is it risky?

Straight Stylus

I download pics, and crop and rotate them, that helps me detect even slight deflections from straight, this one, see the width of the black on either side:

This might not have been a problem, however, if the cantilever is slightly off to one side, that indicates potential wear on one side over a long enough time to cause the deflection to be permanent. Or, it came that way, new from the factory, or it got banged into the side of the platter, and is ever so slightly bent.

This was a stylus only, if it was with a cartridge, even better with a headshell I liked, it is very slight, then I probably would have bought it, had VAS check it for me, ...., 

IOW, you just want to be careful, I was tempted, passed, found another shortly thereafter, dead straight.

patience is an asset, having a rebuilder you trust is an asset.

Was given an expensive Sumiko Palo Santos with cantilever missing. Sent off to SoundSmith to replace cantilever and it sounds amazing. No way I would buy brand new. Now I would buy used carts that need repair when the retail expensive is over $3k knowing retip/rebuilt is cost effective.   

I bought a used Soundsmith cart & had great luck with it.

You take a chance but can get an inexpensive rebuild.

I’ve got another used Soundsmith cart on the way that will be here in a couple days.

E, it is said that the act of measuring coil resistance in a MC cartridge can per se damage the cartridge because meters deliver a current in order to measure R. The current can burn up the delicate coil wire. I’ve gotten away with doing it very occasionally and using an expensive Fluke meter but cheap meters might be hazardous to MC.

I bought two demos and thought they sounded excellent.