Got a response from another seller who stated :
Paraphrased: I am concerned about sharing data that is forbidden by Adsense
So basically saying that because the CPC and CTR are included in the report then it would be breaking the Adsense TOS and he wont do it. I guess that is kind of a legitimate excuse but also means that if a seller wants to say that then any of the above mentioned methods could be denied on this grounds.
Guess it all comes down to intuition, gut and luck.