Cartridge new or used ?


How do I know if a cartridge is new or used and number of hours played ? 1- If it is bought from an individual or 2- Could it be that a HiFi store sells used or a "Demo" without anyone knowing it? 3- Is a cartridge that remains on the shelf of the store for 3 or 4 years, retains its same performance or its internal parts, can harden and lose their flexibility of reading? 4- Is it easy with a magnifying glass to see the wear of a cartridge, if so what would be the best magnification to use?
audiosens
@chakster 

I don’t know who was responsible for the 80’s AT cartridges, but maybe their customer service department may be able to help. 
Ya pays ya money, ya takes ya chances. Glad to hear others have had good luck with preowned carts.
I like the 'used underwear' and ' Ya pays ya money, ya takes ya chances'
If the stylus is user replaceable, go for a used cartridge. If the cartridge does not have a user replaceable stylus, knock your bad self out and purchase..AND consider having SoundSmith retip the stylus. 
You can minimize the uncertainty of the "takes ya chances" part with a dose of healthy common sense and  research.

As I have said it is NOT for impulse buyers or the faint of heart...lol.

Works for me and keeps my pocket a little fuller each time I buy a used cart.

Good luck to all.
  I’ve had mostly good luck buying used cartridges. For my last example I paid 2K for a used Lyra Kleos SL.   To start with make sure you’re buying from somebody with lots of good feedback and make sure their backstory makes sense. For example if they claim 200 hours on a six-year-old cartridge, do they have multiple arms, why does it have low hours? 
 Then considering I’m getting it for 2K off of retail. So even if it has more wear I can retip it for $500 and be ahead of the game.  Then there are those that say it’s not the same cartridge after it’s been retipped. Technically they are correct but in my experience it’s still a very very very similar cartridge.  I retipped a Lyra Delos and I would be hard-pressed to have noticed that it was any different. 
 I refuse to pay the ridiculous amounts they want for new cartridges these days.