Because keeping it cool is more important than keeping dust out. ~Not-So-Handy Andy

Especially considering the fact that, according to submitter DCarter, one of them is half broken.

Submitter Jax describes this fix: The bearings in this fan failed months ago. I kept it running by coating the shaft and bearings with oil as the fan spun. Today the bearings finally failed and the shaft kept popping out of the bearing sleeve, so I took the ink out of a pen, pressed it against the shaft, and put a rubber band against it to hold it in: a 100 dollar motor temporarily repaired with a 50 cent pen.

Protip: widening the tubes makes information stream at a faster rate.

~NSHA

Now user pedrohin's box fan will remember how to stand up.