Excellent post!According to the law the way it is written if you do not know they are prohibited you are fine to sell to them.
So if you list it and ask no questions of the buyer you can not KNOW he is prohibited so you are fine to sell to him.
You are more than welcome to make it more complex than that.The more complex you make it the smaller your group of buyers become.
some things that prohibit a person
being a felon
being under 18 and buying a handgun from a private party
not being a resident of the state