The Latest Scam

I do have a question though- something I have always wondered- can a non-paying buyer leave you negative feedback?

Yes, sadly.

Their feedback will not count only if they lose their ebay registration within 90 days of leaving you feedback. You have to get 3 unpaid item strikes to get deregistered. (Less strikes I think if you have less than 10 feedback.)
 
I do have a question though- something I have always wondered- can a non-paying buyer leave you negative feedback?

THis is very similar to a question I just posted on this forum as well. A fraudulent Ebayer won my item and I want to send a 2nd chance offer to someone but I dont want negative feedback! ANY help appreciated! Please check out my threat as well.
 
Once you filed a unpaid dispute against the not-paying buyer, and buyer failed to respond within a certain period of time (7 days I guess), this buyer will receive an unpaid strike. By that time, he/she cannot leave you a negative feedback. If the buyer leaves you a negative feedback before he/she receives the strike, that feedback will be uncounted (but not removed) in your rating after strike is given.