If you ever want to start a fight, follow these steps.
1) Get a bunch of fiction editors in the same room. (That step alone might be enough, but if you want the sparks to really fly...)
2) Give them the text from any outstanding short story published in the last 50 years. Make sure this is a special version of the text, in which all the commas have been deleted.
3) Tell them to figure out, as a group, where commas should be placed.
It's bad enough that major style guides can't agree on such simple questions as whether
Mary, Tricia, and Alice
Mary, Tricia and Alice
is the preferred way to list the names of three characters. (The Wikipedia entry about that extra comma is the best treatment of the subject I've ever seen.) Yet if you read that entry, you'll notice that it discusses the rules with regard to non-fiction prose. That's probably because in fiction, you can get away with anything if you do it well enough.
In all prose, a comma's primary purpose is to help a reader organize (and therefore understand) text. But in fiction, commas have a secondary purpose: to slow the prose down by making the reader pause.
Think about this passage about a 10-year-old girl named Susan:
Susan, breathless, rattled off all the friends she'd made at summer camp: Toni Lisa Kristen Kirsten Debbie Melanie Other Debbie Gwendolyn Sarah a different Susan Beth Barbie (no for real!) Wylie Jamie Maria...
I left out all commas in the example above because I don't want readers to pause; I want them to feel like they're being hit by a firehose. If readers get lost while reading that sentence, good! That's what it would feel like to have a hyper 10-year-old tell you all that. If readers follow the first few names then skim the rest and move on to the next sentence of substance, good! That's what most adult listeners would do after the third or fourth name—tune the speaker out and wait for real substance to resume. By taking out the commas, I make reading the text more like hearing "young Susan" speak, and instead of feeling like you're reading, you feel like the story is happening to you. (At least I hope you do.)
In fiction, a comma's secondary purpose can conflict with its more universal purpose, and that's where the arguments start. Consider this sentence, and presume it's part of a short story:
So after the party we went to Mike's house.
Should that sentence have commas? If so, where?
My answer is, wherever you want the reader to pause.
If you want the sentence to seem fast, maybe even a bit rushed and poorly organized, then leave the commas out. If the writer doesn't want to have that effect on the reader—if the writer wants the reader to ignore punctuation and focus on the factual meaning of the words—then I say put them in, because readers won't pay much attention to punctuation that does what they're expecting.
What if you, the editor, aren't sure which works better, and you don't know what the writer wants? You can always ask the writer, but you can also examine the surrounding prose. If that prose is written conventionally, the commas go in. If it is not, and the author is breaking traditional rules to achieve a specific effect, I'd probably leave them out, even if the writer's submitted draft includes them.
How do you handle problems like this?