As a cam program/sponsor I can confirm it is normal to look the http referer (along with IP's etc.) of every new affiliate signups at least before the first payout, just to check if this is a fraud. Any program not doing this would be bankrupt soon due to fraud, in fact we see 8 out of 10 new affiliates who signups being fraud (esp. the pay per free lead ones). It means: 1 every 5 new affiliates is good, rest is fake signups. This is not just us, other programs confirmed such dramatic affiliate fraud ratio, we need to check, sorry.
Said this, it is unavoidable that we the programs see also data of those 1 every 5 affiliates who is legit; and if http referer it is not hidden, we can't "unsee" it to forget. Even in good faith, we can get to know the method. But 1) in 99% of the cases we know the method already, no geniuses, 2) We can not always "copy" it, for ex. if a tube owner sends own direct traffic, what we copy? 3) Most tricky methods would cost us more to do ourselves than what we pay to this affiliate, since time is money: going ask skype contacts in chatroom, add them, talk, then spam the link one by one? Just an example.
Further, I tell that rather than hiding (empty) http referer, we often see fake one. Like, they send from place1, but fake http referer of place2. This is mostly made by fraudsters, thinking this looks less fishy than empty or clearly hidden source, but we check the same
Be careful if you put fakesite com http referer rather than empty, you are more likely questioned for fraud, than empty. In case of empty http referer and strange signups we contact the affiliate anyway, in general to see if they reply with a "Sir... " and so on.