You said, "There's no way for any client to dispute anything if you have a papertrail of computer logs, invoices, co-op filed, times and titles for each spot, etc."
See you in court! I WOULD NOT PAY because you can't prove the right ad ran. I'd go to a station that could PROVE my ads ran.
I might be a thousand miles away. Your an underpaid student radio geek who is eating pizza and doing homework when my spots ran. There are tomato sauce stains on the log that make it unreadable. You'd lie, anyway! In your example, you can't prove to me the correct spot ran.
I'd LOVE for you to sue me. I OWNED a station where the previous owner was seldom paid co-op money because he NEVER provided verifiable information. That owner also said they ran alot of religious programs that never "really' ran. THAT happened in 1973. That station owner was about to be sued for fraud (before he died of a heart attack and I bought the station, and made the red ink black within a year). You'd certainly need better verification today.
Your invoice doesn't really mean squat. YOU could tell me anything. LOTS of radio stations don't drop power when they are supposed to, actually jeopardizing their licenses. Why then, should they NOT lie on invoices?
I worked for a few stations, including WAZY, WIND and KMOX. I OWNED 4 (for 13 years) and sold them for a million three hundred thousand in 1985. I also found and sold the frequecies that are now WGLM, WNDZ and some others in the midwest.
Good luck.