Lists the most commonly used tags with empty/missing tag wikis (wiki or excerpt).
Q&A for science fiction and fantasy enthusiasts
SELECT t.tagname AS [TagName], t.count AS TagCount FROM tags t LEFT JOIN Posts e ON t.ExcerptPostId = e.Id LEFT JOIN tagsynonyms ts ON ts.sourcetagname = t.tagname WHERE e.id IS NULL AND ts.id IS NULL GROUP BY t.tagname, t.count ORDER BY t.count DESC