Is it one of those well known brand name "for dummies" books with the yellow cover, and published by the same company that's done hundreds of others?
That link doesn't look like it's for a brand name "for dummies book", and it's slightly cheeky of the author to use the "for dummies" idea if his book's nothing to do with the brand.
I think the company that makes those books just hire people to release the content, i mean it's not a centralized group of authors, anyone can release there but in a way its a bit centralized since possibly you need to get approved by them. I think it's a joke that you have to give those guys royalties if you want to use their infamous "for dummies" cover tho.