Okay, check out this site.
I'm part of the working yorkie forum which is a Yahoo Group and this is something that was brought up and I ABSOLUTELY agree w/ the author and have years of experience seeing neutered/non neutered dogs as clients, whether they be related or just the same breed and find what the author has to say VERY true and I've been saying this for years, but its great to finally have someone of his calibre put it in writing!
(give it a chance, I think EVERYONE can appreciate the last two paragraphs especially!)
http://www.caninesports.com/SpayNeuter.html 
