Some searches have erotica as a separate category when you search on them: See
http://store.kobobooks.com/en-CA/Cat...qkGJjadF625rNg. You can choose another category and not see erotica.
I have also excluded erotica by searching this way. "search term"-erotica, for example, "bundles"-erotica. It is important that there be no spaces at all. If you mistakenly type "bundles" -erotica, you will get a very, ummm, unusual (to me at least) listing of books.
The people at Kobo are aware that this is an issue. Whether this translates into a speedy fix may be another story.