ok, so it sounds like either they're chewing the crap out of it, physically damaging the ends, and/or their saliva is shorting pins.

There are under $20 options like this, but they don't test ALL USB-C pins:

https://www.amazon.com/dp/B09322XTB7/

Your best bet is what's already suggested by blaze1234, as it does exactly what you ask, although "under $20" is asking a lot.