Its not difficult to wipe 99% of the data from a device
The best way to wipe an Android device is to do a factory reset, completely fill the device with music or video podcast files and then do another factory reset. There may be fragments of old directory information left left but the majority of the data will be gone. This works because each location in flash memory can only contain data from one file and so when a device is full then to all intents and purposes the old data has gone.
Biting the hand that feeds IT
