IMO banner exchanges shouldn't allow 'blind link' banners such as:
(from your exchange)
I wouldn't risk letting other people put blind links on my sites.
These sort of banners are also unfair,
and always earn the highest banner exchange impressions,
because they will earn free impressions from each "fake" click.
ie. surfer expects more pics from original site,
clicks "page 2", generates impressions for blind site,
then clicks back button.
Sites not using blind banners wouldn't get this advantage.