SaviCatses:

I am sure you've been sanding and had to whack the paper against something to get the trapped particles out of the paper so you could continue.

Keeping the paper from clogging is the purpose of wet sanding - the paper doesn't clog up.

A side benefit is that as you continue the paper's cutting ability decreases, and you end up using what amounts to a polishing grit. Makes the surface very smooth, as pointed out by Flyboy.

Bill.