it would be better to use an explicit join query and only return the GenreName column
INNER JOIN itemgenres
ON itemgenres.ItemGenreGenreID = genres.GenreID
INNER JOIN items
WHERE itemID = varItem
Using the Where clause for creating the joins is valid, but it's easier to read if you use the JOIN syntax. Also, it allows you to easily modify the query to use a LEFT or RIGHt JOIN, or even an OUTER JOIN depending on how you want the results to act.
I have forwarded this to the documentation team, thanks for the feed back.