Wow, this might be the noobiest question ever....?

How come everytime I see an indoor grow room, the oscillating fans all have their front cover plates taken off exposing the bare fan blades? Even in a George Cervantes DVD I have, he says: "but don't back up into the damn thing, it's spooky" haha. I'm guessing for mold/mildew build up along with hair/dust? Whaddu know that I don't?

Best thing I can think of is to put out more air. Sometimes the fan guards can block a lot of precious flow. That and te possible dust issue.

Most of the time they take of the front grills to clean them and are too stoned to remember to put them back on. I fucking hate backing into those!