First, let me note that I have not yet published any fiction, and am not likely to change my mind anytime soon.
Even so, I still receive quite a few fiction manuscripts, which is what prompts the following comment. I have yet to read a fiction proposal that punctuates dialogue the way I would. It seems to be a common problem, or, I am overly fond of punctuation marks, but when I see a sentence in dialogue like “Get back here you bratty little shit!”, I would add a comma after “here.” Similarly with “Shit shit shit! ”I would render it either as “Shit. Shit. Shit!” or “Shit … shit … shit …”
Not enough commas = big turn-off for me.