What neurovore said earlier--character is voice. That's how I write, so I use all sorts of odd things in my narration that wouldn't fly if I were, say, writing an article for a newspaper. Fiction is fiction...doesn't need to follow the Chicago Manual of Style in every way. I choose my words for effect, and if breaking a rule gets me the effect I want, I break the rule.
It makes for good fiction writing, but I've found out that it's ruined my objective writing...I tend to sound far, far more opinionated/hot-tempered/etc then I really am when I am discussing theories of things. I just automatically word things with "oomph" and it can rub people the wrong way.