What % of affilate sales go invalid?

What percent of your affilate sales goes invalid before being paid?

I think I am at around 25%, I still don't know because I haven't received the payment yet. I was just wondering what other affiliates had experienced.

Also does hostgator ever get it wrong? and if so what is the proper way to contest it? (btw I really love hostgator) :dance2:

:thanks: