Yeah I know but that's why they are used as a filler
I.e. only used to fill extra space that you haven't sold yet yourself.
This is really good for sites that get tens of thousands of uniques per day, it takes a lot of work trying to sell private ad space but if you have a network that can take advantage of any extra space you have.
I use PAN as a filler so its nothing I rely on for a lot of money, its just giving me extra that I would have missed out on otherwise
