Forum Moderators: open
As for using a redirect....many affiliate networks use a redirect through their servers for all affiliate links. It's actually a good thing for the merchants who have loads of not so relevant affiliates.
Are you running your program through an inhouse solution or an affiliate network?
The advantage I've found here is that when banning affiliates, their affiliate URL shows a 404 error, which I can then get removed from search engines etc.
That may be good for you, but it's probably not so good for your visitors that would normally be able to access your site through that link.
Are you really banning that many affiliates? I'd be curious why.