In my experience, there are certain rules that will make a smart playlist fail to update dynamically when on an iPod. Is there a complete (or mostly complete) list of what conditions do this?
From what I've experienced, these break live updating on iPod smart playlists:
*Podcast is <true/false>
*Playlist is <another playlist>
*Album Rating is <0-5> stars
My speculation is that the Playlist and Album Rating rules break live updating because the iPod doesn't do the complex calculations that those require. I think the Podcast rule is a bug and for all I know it's fixed now. I just avoid it and use
*Genre contains/does not contain Podcast
and that seems to work just fine for me in most cases.
Because of this issue, I avoid the Podcast and Playlist rules entirely now, and while I use the Album Rating rule I do so knowing that the playlist it creates won't live update on the iPod and will only get updated when I sync back to iTunes.