“Marks on the underside”

Not sure I’ve ever even looked at the bottom of a piece of gear... seriously, who does that? I’m with the rest. Not worth the hassle. Buyer pays return shipping, get it back, refund. Be done with it. 

Overstate blemishes and detail them in photos. Let the buyer decide and cover yourself.

Always include Hi Rez pics of every surface (underside incl) & describe every mark accurately.

Yup singintheblues.  Seems obvious to us.
Hi res photos will do with just a reference to each mark - It's not easy to describe a mark accurately.

Hi rv, first let me mention that I would never return any gear for marks on the bottom, and agree with everyone it was likely a case of buyers remorse.

The only other thing I can think of is that the buyer is a reseller who works on small margins.  And perhaps his selling description would include the marks on the underside and would eliminate his profit.  Just guessing, nothing else.

Again, I would have kept it, but thanks for posting this.