The main characteristic of a User Friend is that they will not or will rarely return favors for you.
The User Friend's motivation may or may not be intentional. They may genuinely feel and believe that they're a good friend, but in actuality, either their laziness or lack of reciprocity makes them not a good friend.
Kay: Hey John, can you help me fix this file? All of the pages are not the right size.
John: Sure, no problem! Hey what are up to this weekend? Up for hanging out?
Kay: Sure, I'll give you a call!
Kay never calls.
Joseph and Michael, Joseph is the user friend.
Joseph: Hey, thanks for taking me to the airport Mike. I really appreciate it.
Michael: No prob man! Hey, do you think you could watch my dogs for the weekend while I'm out of town?
Joseph: Oh, I've actually got company over that weekend. Sorry bud!
Joseph did have company, but very well could have taken a couple of hours throughout the weekend to take care of Michael's dogs.