I'm currently working on my first MG manuscript and I plan on cleaning it up and querying it once it's finished. In addition to this novel (and past projects that I've set aside), I participate in National Novel Writing Month every year. The results are usually self-indulgent fun little novellas that I write primarily to entertain my friends who also participate. They're not things I would ever consider selling. One of the "prizes" for completely NaNoWriMo is a free proof copy of your novel at Lulu (this year it's through Amazon's CreateSpace). I usually order the free proof and then publish the book through Lulu so that my close friends can also order a copy of my book and I can order a copy of theirs.This is the sort of explanation for self-publishing that makes perfect sense to publishing professionals. It says you have a realistic idea of the range of your work (some of it is just for fun; some of it is professional enough to send to publishers) and a realistic idea of what self-publishing is for (mostly just personal use).
My question is this: will these little forays into self-publishing have an effect on eventually querying/potentially publishing my MG novel or any other future projects? The NaNo novellas are not children's books and haven't been marketed aside from an e-mail to my NaNo writing group announcing that they're up and available. I wouldn't, of course, mention them in my query, but Google has the ability to pull up all sorts of things these days.
As self-publishing gets easier, cheaper, and more wide-spread, even editors with a congenital prejudice against it are going to have to accept that it doesn't necessarily mean the author is a nitwit.
What editors are justified in worrying about is if your badly-edited and crappily-illustrated self-publishing efforts are on Amazon or some other easily-accessed place. Then they could be seen as negative publicity-- readers who might truly enjoy the book you published with Holt (eg) could be turned off by the book you published at Lulu, if they see both books in the same place.
You're building a name for yourself, remember-- and you want the qualities associated with that name to be consistent, whether it's "fun / character-driven", "literary / romantic", "suspenseful / humorous", etc. You don't want to confuse people with "fun / ugly", "literary / boring", or "suspenseful / like a bad acid trip".
And you know who's particularly good at quality-controlling an author's work? It's usually not the author.