I have ghost unread items in http://export.arxiv.org/rss/cs after the DO outage.
I don’t think they’re truly ghost, however. Currently showing 66 items unread while the view pane (on “feed”) is showing “No stores to read” and there’s nothing in the summary view - but this feed does typically have 50-75 new stories nightly. So I think there are 66 unread stories in the feed.