Affiliate scrubbing/shaving :
Scrubbing is when an advertiser (not the network) scrubs out bad leads and you do not get paid for them. This is very common and happens on a majority of the advertiser pages. This could be as simple as scrubbing someone from another country when the advertiser is only asking for US based leads or as complicated as the lead having bogus information such as a fake email address (e.g., [email protected]).
Shaving is different. Shaving is when an affiliate network shaves leads from your leads. So maybe one in 100 of your leads does not get counted. The network still gets paid from the advertiser for this but you will never see anything. There are times when shaving is intentional (and some networks have been proven to shave) and sometimes when it is unintentional. Either way, it can be prevented by simply split testing the offer across multiple affiliate networks if possible.
Always remember that you should not accuse anyone of shaving unless you have a statistically significant number of leads to prove it. If you only have 10 leads per day on average and one day you have 5, it doesn’t mean the advertiser is shaving. It could mean a lot of things.