Why do so many sellers take offense to offers on their listings?

I am usually more interested in the quality of the buyer so as to avoid the risk of problems after the sale, which is a practice that has served me well here for over 20 years.

A very good point. I've always been a value shopper, not a price shopper. 

The only time it's a problem is when a seller thinks his stuff is worth 95% of retail and a buyer that thinks 50% of retail is a good starting point. Anybody that starts off with NO LOWBALLS is just wasting my time. If you get a low offer, just say it's too low, you don't have to make a big deal out of it.