Since my scanner bed is made of glass, I use Windex or any glass cleaning product.

What gives me trouble is the dust particles that seem to congregate on the under side of the glass. You would think the scanner box was sealed, but since there is a light bulb in there and it can get hot and the case has breathing slots. Add to that, the mechanical movement of a scanner seems to produce a static charge and in my environment, dust builds up on the under side of the glass.

But to answer your question, I just use Windex. BUT, you need a lint free cloth or material to make it streak-free. I use newspaper. Preferably a sheet without pictures and not the glossy colored ads.

Jim