Is the search engine giving different results for different people? If I search for Roger Zelazny on amazon.com in Books, every result returned on the first page is by Roger Zelazny.
http://www.amazon.com/s/ref=nb_sb_no...=roger+zelazny
In the first five pages I see 60 results, of which 51 are by Roger Zelazny. Of the remaining 9, Zelazny wrote the introduction for two, and the other seven are spurious - but are by authors who are often grouped with Zelazny (Norton, Bester, Vance) so could be viewed as 'if you like Zelazny you might also like this' recommendations.
51 out of 60 seems pretty good to me, and I can see why the others are in the list.
Graham