I violently disagree.
And I found out yesterday that I am in good company. As yet another means of learning more about the craft of writing, and for sheer pleasure, I listen/watch lectures from The Teaching Company. (As an aside, I've never bought anything from this company that wasn't outstanding.) Right now I am watching Dr. Timothy Spurgin discuss the English Novel. Jane Austen was the subject of the latest lecture. She was one of the first novelists to grow up reading novels,since the first novel, Pamela, published 1740, appeared only a few years prior to Austen's birth in 1775. Austen read voraciously, as we would expect a great writer to do, but she also read widely, including what we would consider to be junk. Austen's close-knit family also read aloud in the evenings, which would have given Austen the opportunity to see and hear what worked and what didn't. This reading aloud surely helped Austen develop her ability to create first-rate dialog.
I know I've learned just as much about good writing from reading the low-life stuff as I have from reading the classics, because when I read something that just doesn't work for me, I ask myself WHY in quite specific terms, and vow not to imitate. Besides, sometimes you just have to have a hot fudge sundae, because it's fun.