I'd like to have several audiobooks and/or podcasts on my Nexus 7, but every time I put any MP3 files onto the device, even if I make my own folder for it or some such, Google Music detects them and then adds them to its list of files.
This is a problem, because I'd love to be able to use the "Shuffle All" feature, but then it ends up shuffling in chapters from the Audiobook. I don't want it to do that at all.
Well despite the comments about a .nomedia file not working in the newest version, on my fully updated Nexus 7 (as of April 2013) using a .nomedia file prevents the audiobook files from being scanned and listed in Google Music.
Some extremely simplistic testing seems to indicate that a single .nomedia file at the top of a directory tree is enough to prevent all sub-directories from being scanned. In the case I talked about in my question, a .nomedia file within the "audiobooks/" directory would prevent all books from being scanned, even if each book was a collection of .mp3 files within its own directory.
Adding .nomedia to the top level of a directory has worked for me, but also had to flip the source from "On device" to "All music". I am using Android 5.0.1 on an nVidia Shield Tablet.
I noticed that when I added .nomedia to my Podcasts folder (which I didn't want showing up in my Google "Play Music" app, it only disappeared once I changed the source from "On device" to "All music" and back again. Now it's working as described above. My Podcasts have been removed from my music player, but still show up in my Podcast player.
Utilizing .nomedia (using ES File Explorer to simply create a file called .nomedia like Lokathor), all of my ringtones, podcasts, and notification sounds disappeared from Google Play Music. I'm using 5.1 on an HTC M7. (8/4/15)
Running Lollipop on a Note 3, I added .nomedia and restarted the phone, and it did NOT clean up. Then I flipped off Downloaded-only, and flipped it back, and "shuffle all" still was not cleaned up. I then restarted the phone again, and it was finally cleaned up.