I'm not sure if this is happening for everyone. I felt like talking about something, and this came to mind.
I was playing Left 4 Dead 2 with my big brother, and 4 other people were in our friend-only lobby. A guy named "2-hand disfunction" or something came in and complained about lag, even though we haven't ever seem him in any way.
He left, though. Is this happening to other people?