Interesting result. I recently accepted for review a book that is free to download, and then wondered if I should be doing that. I contemplated protests along the lines of I'm a writer/publisher with books that are for sale and dependent on getting the news out via reviews etc, so not happy you're passing over my titles to review stuff that anyone who is interested can download and sample for themselves at no risk as they're free.
You people are much nicer than I thought, or you're planning to give lots of stuff away
My policy on self-published books is that I will review them as long as the author has some previous track record. For example, when Andrew Hook launched Elastic Press he tested the water with a collection of his own work, so in effect he self-published, but most of the stories in that collection had already been previously published by other people. Similarly, my only foray into self-publishing was with a novella that had already been accepted by a publisher, who then closed down the month before it was due to be released. The self-publishers I want to weed out are those who probably can't get work into print by any other means, and yes, a few omelettes get thrown out with the bath water, but you can't make babies without breaking eggs. (See what I did there?)
And, if you're desperate for a review I'm easy to fool - if I get a request from Big Boy Publishing Inc to review the latest novel from hot young talent Joe Bloggs, I don't have time to check on BBPI to find out if they're a front for Joe Bloggs, so I'll probably say yes if you ask nicely and nothing else sets the alarm bells ringing, though once the book gets to me there's still a fair chance it won't get reviewed anyway.