I did a factory reset on a Samsung Galaxy S2 like this:
- switch off phone
- hold down buttons Volume Up, Home and Power until phone boots into "Android System Recovery" mode
- select wipe/factory reset and confirm all questions
As expected, after the factory reset, all apps were not installed anymore.
But this does not seem to have worked for the file system: On the file system of the internal USB memory (/storage/sdcard0), I see many folders of previously installed apps and also some which I had manually created before the factory reset. I think that a factory reset should delete all these folders, because e.g. the WhatsApp folder contains all my personal messages. I think that if a function is called a factory reset, then afterwards personal messages should be deleted. So what's wrong here?