To get rid of all the old results (say you've been away for a couple days) in the RSS feed, you must turn off the timer, click Refresh, then turn the timer back on. This may cause some unecessary server load for grabbing the feed a couple of times, but also is a lot of steps just to have a fresh look because of all the coloring going on.
A simple "Clear" button to empty the RSS results tab would be awesome when the timer option is enabled.
Edit: Just saw that you can right-click and clear. Didn't see a delete button, so ignore me. It is amazing how much is available in the software but not easily discoverable. Thanks for all the hard work!