Operating the headlight warms the assembly, expanding the air and venting excess volume/pressure. When the headlight is shut off the assembly cools, contracting the enclosed air and drawing humid environmental in to equalize the pressure. The humidity moisture condenses in the interior and the droplets have no way to run out and accumulate for you to see the ‘wetness’.I would be more concerned about how water got there in the first place. Seems to me that, if not corrected, it will happen again.
As kevace82 suggests, it's very easy to remove the headlight assembly. You will need a torx bit with a long extension to access the rear screws that only need to be loosened 1 turn.But how easy/difficult is it to remove it? I’ve seen a YouTube video of someone removing it on a newer BMW and that was a nightmare! Just removing the plastics to get to it and the hidden screws is like a 45 minute ordeal or at least it felt that long!
Apparently I exaggerated; it took a little over one hour. I just left the blow dryer in and checked it a few times, moving it once or twice.I don’t think the 2006 has the same assembly. Wish it was that simple. You actually blow-dried it for 2 hours?! That’s really long. I would’ve given up after 20 minutes.