I watched the excellent documentary, Catfish. The sound was done by Coll Anderson.
There's debate as to whether or not it is real. I wonder if we can tell from the sound if it is or not.
When they are meeting the family, which supposedly do not know that they are filming, they all sound decently miked. This means (I think) that they would either see a boom or have had a radio mic put onto them...
ps: this is an after thought, I would need to watch it again to make sure.