For instance, click the search function in this database and enter "button graphic" and it trawls up nothing. Press back and enter "submit button" and it'll find a few documents containing both button and graphic in the title.
Hardly the first example of having to second guess the search engine and we're developers for chrissakes. How many users and sales am I losing because the users can't find what they're looking for with simple keyword searches?
And don't even get me started on the "...x responses)" to docs that have no responses at all.