In past posts about akregator (the RSS reader for KDE), I have noted that it loses count of the unread articles, and gets maybe one or two off.
Since installing opensuse 13.1, I had a run of several weeks with the count being correct. But then, around 1 week ago, I began to have problems with counting once again. The way this happened gave me a little insight.
I noticed a couple of new articles that were 9 months old (from February 2013). That surprised me. So I checked the akregator settings. It turned out that I had archive settings configured to keep all articles.
Previously, I had configured akregator to delete older articles. I seem to remember that I had set the limit to 60 days. Checking the archives, I had quite a few articles that were 3 months old. So I changed the setting to delete articles older than 31 days.
A few hours later, I noticed that the count was off by 7. The akregator GUI did not show any unread articles, but when I hovered the mouse over the tray icon that said there were -7 unread articles. I shut down akregator, then restarted it. That left me with a correct count. The next day, the count was off by 1. Again, I stopped and restarted. The following day, it was off by one again.
So it looks as if akregator is losing count when it cleans up old (stale) articles.
With that experience, I have now switched back to keeping all articles. My plan is to switch to a 31 day retention every two or three months, give it time to clean up, then go back to keeping forever. That way, I will have to put up with the losing count only during those cleanup periods.