I think we've all read the book so chock full of old, weary metaphors that we couldn't even plow through it. In fact, just last week, I decided to pick up a "master of suspense" and read, "As the terrible pain invaded his upper arms and chest, Evan genuinely thought he had been bitten by a Tyrannosaurus rex." I made it about three more pages. When I got to "Aw, gee, he was such a weed!" I had to set the book aside.
Fresh writing eschews the cliche and seeks the image that glows -- the image that lingers with us, makes us sit up and think, "Ah, yes, why didn't I ever see it that way before?" Comparing two unlike objects only works if it hasn't been done a million times before.
On the other hand, they can't entirely distract us from the plot at hand. Scribbling out, "the thin ribbon of water wound about the belly hairs of Mother Earth," will most likely cause your readers to spurt their morning coffee. Or throw your book across the room. Or abruptly stop reading your blog post... ;D
So give me your best OR worst metaphor/simile. It can be one you've created or one you've found. Only needs to illustrate the fresh or the cliched.