What info does the Adsense code collect from our pages?

I was wondering whether cloaking is at all possible nowadays with Adsense, given the fact their javascript code can theoretically collect page contents and send it to Google for analysis, to know how the page looked like when the ad was triggered.

Does anyone know if Google in fact collect that type of information? If you even got banned from Adsense due to cloaking, what was your mistake?