Or is it just people?
I have 4 Lexus wheels listed. Had a lot of people email, three offers, not one show up.

One gentleman asks if he can buy 1 wheel. I have a set of 4 and don't need or desire to keep three.
I say Sorry, but I want to sell as a set and explained my reasoning.
He gets PO'd.
Two weeks later he emails me again saying "Sell me 1 wheel!!!!!!"
I say "fine... I'll sell you one wheel for (full price) and you can have the other three for free."
He gets pissed again and tells me no one would buy a set of used wheels, blah blah blah and that he found one.
Here's a hint, people... if you don't want what I'm selling... don't bother emailing me. Pretty simple, really.