Damn I learned about that but it still surprises me.
I know there must be payola here in France too but I don't think it's that blatant. Or I'm not paying attention enough lol.
One way to know is to pay attention to how many times a specific set of songs is playing. If those sets of songs are playing every 30 mins to an hour there's a good chance it's payola backed unless your area is big on radio requesting(when I mean big on requesting I mean multiple people are requesting songs every 30 mins to an hour).
If your radio station plays varied songs(meaning the same set isn't playing every 30 mins to an hour) then it's probs not completely payola driven.
The biggest give away are songs playing every 30mins to an hour continuously for months. Sometimes older songs do pop up naturally, but no one is requesting an year old song to be played every 30 mins.
Another dead giveaway is if there's variation of the songs played on diff versions of radio channels. a lot of the times the main channel plays the payola songs while the other versions play actual requested songs mixed with the payola.