Guidelines aren't really guidelines. They're more like a set of rules, really...You know, written in stone, with the first being "Thou shalt not ignore the following information." I am going to look like the bad guy here, but let me tell you something important. As an author and as an editor, I have some advice to give anyone who ever wants to submit to any publishing company in the world....
Adhere to the guidelines!!!!!
As an author, I remember reading, rereading, and then checking every single bit of a publishing company's submission page in an effort to make sure I crossed every "T" and dotted every "I" exactly how they wanted. I knew then, and even though I'm multi-published I still know now, that being published is a privilege. It's insanely important to follow formatting guidelines whether you like it or not. If the font they want is vastly different from what every other pub wants, then you save the file under a different name like "Author Name_Story Title_Publishing Company Name" (unless they tell you to send the file with a specific name format, then you do it their way.
The point is, yes it can be a little difficult to remember how publisher A wants it compared to publisher B, but think of it this way; you are begging them to buy your stuff. You aren't going to buy a product that's been presented badly, so why do you expect the publishing company to do so.
Think of it like this: You are at a restaurant. You see a photo in the menu of a really nice meal that looks simply delicious (blurb) and you order it...but when you get it the food is misshapen, mixed together, and totally unappealing (manuscript improperly formatted.) Disappointed? You bet. Frustrated? Damn right! Now, do you eat it anyway, or do you send it back? Well, if it looks salvageable you might pick through and eat it, but you're still going to be disappointed as you eat it, aren't you? Otherwise, you might either just walk out or send it back (rejection).
Okay, so I'm switching to my editor hat now. Cue the fire and brimstone! When our guidelines specifically say, "If you don't format it according to these really easy expectations, we will reject your manuscript," then by god format the friggin' manuscript accordingly. When I get manuscripts where the author obviously hasn't even tried to follow guidelines (or even put any effort into researching how a manuscript should look) then my first thought is, "They don't really care whether they get published or not." I get mad. That's right, you heard me. I actually get so mad I have to disappear to one of my gaming consoles and mass murder goblins or some other monster because if not I'll risk my job by shooting back a snarky e-mail.
I received one the other day though that takes the cake. And I quote, "I did not format according to your guidelines because I wanted to be sure you wanted the manuscript first." What the fuck, sir? Really? Wow, my opinion of you just dropped in the major negative. If you aren't going to put forth the effort to do something as simple as formatting, well then I guess I don't feel like putting forth the effort to reading it. How's them apples?
And for the love of any god that might care, please, please if your publisher says to send in the full manuscript and not partials on their sub page, don't send them freakin' partials! When I receive a manuscript, nothing makes me angrier than either getting a query letter or getting only a few chapters (this does not apply to my in-house authors who I already have a working relationship. I know you girls are reading this and I bet your eyes just went wide with an "OMG, I bet I've made her mad at me," look. *snicker* No worries, you are all safe.)
Before I turn into a snorting, foaming, wild animal I'll end this rant. Please, if nothing else, take away the following lesson: Format according to your publisher or risk being rejected. ~ D. F. Krieger