I have nothing against self-pubbed books. Let’s get that out of the way right now.
Why then does it matter how your book was published? Because some methods, publishers, have reputations. Some work harder on their final product. Some only offer what the author can pay…wants to pay.
Experience is a pain because we all run up against it even when we’re different than the ten or more who showed up before us.
Reviewers have limited time on their hands and, yes, if you did any cutting of corners just to get your book out, well, sorry, but we do consider our time invested in reading. Your choice in publishing isn’t an automatic decline. It goes hand in hand with all the other bits of your request…information, tone of email, etc.
The key though, the main reason on the “how” factor getting your review request declined…hiding it.
Never hold back information when sending in your request.
Never hide anything, reviewers will find what you don’t want us to know.