I've never seen internal (Wouldn't they get covered with smoke reside?)
I can say from experience...I own a Rec Tec, and yes, those lights stay pretty covered in smokey soot. Back before the novelty of it wore off, I used to remove the glass cover from the light every few smokes, and carefully clean it in some dishwater or in the dishwasher. But it would just be covered in soot again after my next smoke. Most of the time now, I never even turn the light on, and to be honest I usually forget it's even in there.
I've never seen internal (Wouldn't they get covered with smoke reside?)