Buying a used tonearm or cartridge is kinda like buying used underwear. Who wants that? There is nothing "safe" in buying some thing as fragile, delicate, and prone to damage as a cartridge or tonearm I know there is a guy here who always recommends cartridges that are 50 years old but he’s in the business of selling them so that colours his thinking.There are a lot of us audiophiles who take great care of their stuff, especially here on audiogon. Sure there’s additional risk with delicate cartridges and arm bearings, but the discounts can also be large enough to mitigate them - especially when you can see the seller has a long track record of analog enthusiasm, 100% feedback, and offers very detailed pics. You’re not buying this stuff from a DJ.
I’ve bought plenty of arm & cartridges both new and used, and have gotten amazing gear from both sources.
It’s not a hygiene issue, anyways, like you underwear analogy. That would be closer to buying used headphones, though just look how robust THAT 2nd hand market is! Again, someone selling a $4000 set of headphone is very likely to be a clean & diligent person.
Though I have to agree on one point in particular - the CONSTANT recommendation of "buy yada yada NOS MM cartridge" for literally EVERY cartridge inquiry is ridiculous lol