Most people with mics will either
A) say nothing and you will just hear them viciously mashing their controller
B) Be playing loud and obnoxious music
C) Vacuum in the background
D) They have it on to talk to a person right beside them
E) They just talk trash
F) They might be well-mannered and enjoyable = new friend?
In summary, approximately 1/6 chance of finding someone worth talking to.
This was my theory long ago, and I may have proven myself right.
Almost every time I run into people with mics whilst searching, they disappear. My theory is that these people with mics are goof balls playing on the PS Vita with the mic on. For some reason, these people press the home button or something that boots you out of the search/match. I would know this for 2 reasons...
1 - It's a habbit for me to check my inbox every now and then, and I have Do'h moments while searching. When you go back, you're at the home screen or character select.
2 - When I found a player, once, I heard a "Select your character!" from another mic user... What? Exactly.