A friend of our family published a book last year. In the spirit of solidarity, I bought a copy and read it. The first warning light went off before the opening paragraph - the book opened with acknowledgements. Ok, unconventional, but fine. No mention of an agent. Ok, maybe I just couldn't pick out the agent's name, or maybe the author sold directly to the publisher.
Within pages I could tell that this was not prose that would have passed muster with my writing group. Too many commas, too many adverbs, and, most damningly, too many fluctuating emotions on the same page, paragraph, or even (the horror!) sentence. I read about 50 pages before loyalty could compel me no further. And I was grumpy all that morning about the wasted time - time I much would have rather spent reading a good book. I found out later that day that the book was, effectively, self-published.
Obviously readers often find books they're disappointed with. But I think the vetting service provided by agents and publishers often - not always - helps narrow the field. I recognize that there are exceptions and that some self-published works are quite good, while many (many!) traditionally published books are horrible. But as the floodgates open, how is a reader to defend herself and her precious time? I sure hope interpid book bloggers more brave than myself will do some winnowing and recommending for the rest of us.