Everybody gets fraudulent/invalid traffic, it's just the nature of the beast. That doesn't meant that you are generating that traffic, it just means that your domain(s) will and may be getting some type of bad traffic. The problem is when more than a certain percent is bad traffic, I don't want to give a percentage, but it's rather high. That's when you have to start questioning what is happening.
Let's say somebody is sending us hits from PTR sites, if 1% of it is PTR, it's hard for me to say if they didn't buy the domain and that PTR traffic was there. But if say 50% of all traffic is from PTR then based on the fact that PTR traffic is not allowed, I would either terminate those domains or the account depending on how the traffic is being spread out.
At least 20 times a week, I am sending an email to some of our partners asking them to point a domain somewhere else, or asking them how they are getting certain traffic. We never want to send people away, but sometimes traffic on certain domains are really bad.
When I tell our providers this account has been terminated on say the 28th of the month, I lose the entire month. Not just the past week or pay period. So even though I have paid somebody for a pay period, I won't even get paid for it. I don't tell them these clicks were legit and these were bad. It's an all or nothing type of thing.
Donny