I guess there is a degree of dishonesty that is why we are constantly trying to weed out the duds and support the programs that are considered to be honest by most of us.
By the way, if you have a program doing the counting you can program whatever you want. You could easily just implement a rule such as – only count 85% of the traffic that is coming in. Just an example, it´d have to be more subtle including ip targeting etc. but again auditing can catch those things and audits do take place. Consult the APCW for more info.
One more thing, don´t put all your eggs in one basket. Try to get feedback from people you refer so that you may be able to do a little auditing yourself;)