Guidelines for buying used speakers (as in, are there any?)

Biggest problem: shipping. FedEx has destroyed two pairs of speakers I shipped to buyers. They spend all of their time explaining why they did not have to pay for the damage they caused. 

You need to open the boxes immediately and complain the same day. The burden is on the buyer. Once I paid for all necessary repairs on a pair of B&W 803Ds.

My standards/rules for purchasing used speakers are:

100% positive feedback ratings from the seller. 

"Local" seller where possible - although I've driven 250 miles to Massachusetts twice to pick up a pair of Ohm Walsh 2's and then a pair of Thiel CS3.5's...both worth the trip. I've driven to virtually all the boroughs in NY for others, including 3 different Maggies, Von Schweikert, Dynaudio, Totem...

Original owners. Unmodded in any way. 

In November of 2014 I picked up another pair of Thiel CS3.5's from an original owner in NJ. Now 30 years old they still sound wonderful. 

99.95 % of the members here truly care about their reputations like myself, so that rating truly matters. I have had one purchase go south here during the course of my tenure because the seller lists (and still does) one address yet ships from another - in a different state no less! 

A'gon members tend to take better care of their stuff in general, period. Buying here is a good course of action. 

Buying used speaker is very risky if you can't hear them in person.Good luck.