At a guess, it doesn't matter how clean the air coming out of the HVAC system is if you're sitting near or talking with someone who's sick.

Trump usually does get it exactly backwards, to be fair. If he's accusing someone of something, it's because he's doing it. If he's claiming something, it's probably the opposite of the truth. He's remarkably consistent about it.

In addition to what others have said, it also gives you an indication of how well leveled your bed is in the immediate area of the print.