We have no problems at all with test signups. On the contrary we appreciate them. The process to be as impartial as possible, we just ask that affiliates notify us after for two reasons: 1) so we can credit you back for the test and 2) let us know additional details, such as the surfer experience of our signup process and possible ways to improve it.
It's an amazing concept that there are sponsors that have such fantastic natural conversion ratios to their sites (especially the large cookie cutter programs) that they wouldn't be fighting to have the best ratios out there. I would image some reverse shaving taking place to pad the numbers and get an affiliate buzz going. But those would only be fleeting good results that would show up soon enough.
Other factors to consider are programs that have their affiliate rebills turned off after a certain number, and there are probably a few programs that don't have their programming act together. Meaning there are holes in their signup process with a custom script or their post back scripts are not working properly.
Good thread
