When a writer sends me his/her work to read before publication, I do my best to be thorough and honest, and to catch all the missteps I can, so that when the work finally does reach publication, it can be polished and professional.
Of course, the end result is not my responsibility but the author's. Still, it can be irksome and somewhat embarrassing to read the published version of manuscript I worked on, and find that the author didn't hear a thing I said about (fill in the blank). Usually -- no, always -- these circumstances are the result of an amateur author who has not yet learned the value of a good and merciless rewrite, or who thinks the first draft is "most pure" and therefore inviolable. Generally, the authors can't find any takers for their masterpieces, and therefore the manuscripts end up being self-published, or being accepted by "low-rent" publishers who play on writers' egos but don't do the hard work of making sure the material is truly ready.
Self-publishing one's work has legitimate and practical uses (niche markets, short runs just for family and friends, and so on), so I can't and won't knock its existence. And there are rare -- I repeat, rare -- occasions when a self-published work is picked up by a larger publisher and becomes a bestseller.
And then there are the writers whose work must be proofed, and sometimes edited, before publication in a magazine. Wow, is there some authorial arrogance there, when writers whose work -- in obvious need of some spit-and-shine -- refuse the polish and demand a return to the stumbling sentences, rambling paragraphs, or confusing dialogue that was their original piece. These people have obviously never worked for a newspaper, where the editor gets the final say on how a story appears in print.
I know what it's like to be edited or critiqued, and to have my work picked apart. I know what it's like to receive advice or suggestions from someone who knows what he's talking about, and from someone who has absolutely no clue. I've learned when to accept advice and when to pitch it out the window. And I'm still learning. (Case in point: the stumbling around, getting-lost-and-finding-my-way-again method of storytelling that has been my experience so far with the science fiction serial for Ray Gun Revival.)
But I also know that my hardest critic must be myself. My most acerbic and ruthless editor must be myself. Nothing is precious. Nothing is too sacred to be re-examined, re-arranged, or deleted. The end result is a stronger story -- and that's what it's all about.