I bought Office Suite Pro for 14$ or something on a rooted Android phone. Having access to the private data folder of the app (/data/data/...), I could read the content of a sqlite database created by the app... in which there was reference of all the files from the userspace storage (/sdcard).

According to their privacy policy, they collect all the "data needed in order to improve their services and offering" and "can provide these data to third-party" for that purpose.

Paying for an app on android platform is no assurance the app actually respect your privacy.