Comment by chermi

Well, I only ever cleaned them fully in grade school. In undergrad I TA'ed on whiteboard, in grad school it was unfortunately all whiteboards. Except for the rare literal "chalk talk" mini-conferences I was fortunate to attend, where I just erased what I had at the end, no full cleaning. So, I guess I just never "saw how the sausage was made" and implicitly assumed the worst.

Or my grade school never knew better, which is quite possible given its size/location. Or they thought it was funny to make kids deal with all the dust?