I'm curious how you define "bogus" referrals.
New accounts with no activity?
A non-activated account?
Accounts created from temporary email providers (ie: Mailinaotr)?
New accounts with no activity?
A non-activated account?
Accounts created from temporary email providers (ie: Mailinaotr)?
You could also put a cookie on the users computer, so you know if that cookie is present for 5 subsequent signups that have little/no activity, it's probably a cheater.