There are differences of opinion among book bloggers as to the value of self-published novels. Some specifically note in their review policy that they do not accept self-published books for review. Others, like myself, are wary but do not rule them out entirely. And I'm sure there are some bloggers out there who swear by them!
Personally, I'd like to suggest the following: there is nothing inherently bad about self-published novels. Just because the book is not under the label of a traditional publisher does not mean unequivocally that the book is of any lesser quality. It doesn't necessarily mean that the book "wasn't good enough" to be accepted by a standard publishing house. Sure, it may have a rather unsightly cover, but we all know that covers do not translate to the material within. And traditional publishers have been known to come out with some cover eyesores as well.
Like really awkward kissing covers.
Or the re-designed Nightshade series covers. (Seriously, what were they thinking?)
But books that go through traditional publishers come with one decided advantage:
THEY HAVE BEEN EDITED.
As in, they have gone through several readings by another pair of eyes, looking at the story from a structural perspective, looking at the story line-by-line stylistically, and then finally copyediting for consistency and proofreading for errors.
I don't pretend to have loads of editing expertise, but I've taken enough courses and read enough books to know how essential this is in making a story readable. Authors are too close to their material to objectively see where the plot holes lie or the world-building falls apart. Sure, there are ways to achieve a better distance from your story (if you're interested in the process of self-editing, you might want to check out Susan Bell's The Artful Edit: On the Practice of Editing Yourself), but the best way, in my opinion? Get someone else to look it over.
Of course, it can be argued that some self-published novels do very well, commercially speaking. There seem to be other readers out there who don't mind the grammatical errors and substantive inconsistencies that drive me crazy. Perhaps there are two different breeds of readers: those who can shrug off the errors and whiz through books that read like the first draft of a manuscript...and those who can't.
Honestly, I'm not sure I can really understand the perspective of a self-published author who does not bother to get someone else to edit their work. Do you truly believe your story is the best it can possibly be when you're the only person to have set eyes on it? Do you only care about the money that's coming in, not the quality of your book? I can understand where financially there might be an issue, but if you can't afford an editor, at least try to get writer friends or beta-readers to point out the problems. Because you can be J. K. Rowling and your work will STILL need to be edited.
It's nothing that should be taken personally. Writing is a craft. So is editing. An editor can only do so much with the writing they are given — and a writer can only accomplish so much without an editor. It's a symbiotic relationship that, when it works smoothly, results in something greater than the sum of its parts: a truly worthwhile story.