The simple solution is to uncheck the tracks in your iTunes library.
I also experimented with a smart playlist to ignore 1-star rated songs in the Genius playlist, and hunted for any way of telling Genius not to use 1-star rated songs. However, this solution is far simpler and works unless you use one of unchecked songs to build the Genius playlist.
This might be obvious to some of you, but I don't uncheck tracks in iTunes very often -- only when importing. I hope this helps anyone else out there who might have a case of buyer's remorse that the Genius can't let go.

