Seems your app scans the whole internal and external memory and adds the files to the app playlists. I guess it might be a good idea but as it also adds podcasts it really isn't. Shouldn't it scan preset folders that contain music on phones (e.g. synced with Kies) or you could also/instead point the app to a music directory (e.g. you've manually copied to a SD card).
Though in one way it was good, now I know many apps don't really remove folders when uninstalling. It added podcasts because Doggcatcher left files behind when I "uninstalled" it.
Actually my app doesn't scan anything. It retrieves the list of songs/albums/artists/genres/composers/playlists from the Android media database. Android's media indexer is what scans the storage for media files. My app queries the database for all audio files that Android has labeled as "music" in the database.
I believe Android will categorize podcasts as music if they're not stored in the "Podcasts" folder. It may also look at the genre to determine the type of the audio file, but that's purely a guess.