I agree with Lee and think that sponsors should auto-approve new affiliates.

But I don't think it's unreasonable for a sponsor to include a clause in their TOS that says they can terminate the account at any time (actually, I think most sponsors already include this, right?). Then the sponsor can check out the affiliate at their leisure and if they see a problem, pull the plug. This is the "innocent until proven guilty" approach that I think most people agree is fair. The sponsors that require pre-approval are taking the "you're guilty until I find out otherwise" approach and I could see why it would frustrate honest affiliates.