When the home owner meets me at the street curb to tell me that he's lived in the house for 37 years and did all the work himself, including the recent renovation, I pause slightly to get some extra paper, some fresh batteries for the camera and voice recorder, and some extra red pens. I know I'm going to have lots of notes to make.
The picture below shows fiberglass insulation batts in the attic. Right there in black and white—ooops, sorry, I mean red and brown—are the instructions for how to install this thing:
Warning: This facing will burn. Do not leave exposed. Cover with approved building material in contact with facing. Keep open flames and other heat sources [such as the electric wires laying on top of it!] away from facing. See package for warning, fire hazard and installation instructions or call 1-419-248-8234.

Since San Diego has a lot of ESL and other Spanish-speaking citizens, Owens-Corning was kind enough to repeat the warning in Spanish. At least, I think that's Spanish. I hope it's Spanish because I've just added a second word to my Spanish vocabulary: Advertencia means Warning. (For interested readers, the first word in my Spanish vocabulary was margarita. LOL)
In this specific case, my notes tell me that the general contractor for a brand new subdivision met me at the curb to tell me that he hired only the best subcontractors and that he would be surprised if I found anything. Well, he was surprised. He did call me a couple of weeks later to thank me because his subcontractor apparently had done this in all the homes, costing him quite a bit of money to have them all redone.
Generally, with fiberglass insulation batts, if you can see the facing, it's been installed wrong, even if the warning is not there. For readers who have worked in a hot attic with fiberglass, you know that by the time you finish, you're itching up a storm, so many people put the exposed fiberglass face down so that they won't get as itchy.
Great blog Russ, thanks!!!