User blog comment:Sarah Manley/Followed pages - a new way to stay up-to-date on your favorite wiki pages/@comment-13301-20100509085411

Another reason to not show up deleted pages on the public watchlist: Vandals and spammers who created spam pages with inappropriate titles have those pages in their userpage watchlist, and they're now shown publicly, so no matter if we deleted them because they can post on that userpage what they want.

Edit: Even worse, the userpage watchlist is also shown on DELETED USERPAGES: