In writing, there are some things you never want to get caught doing by accident. These are three of them.
One: being funny. Intentional humor is hard to do — humor, like horror and erotica, is a genre that works or doesn’t on the basis of the emotional effect it has on the reader, and if that effect is missing, no other virtues in the work will make up for its absence — and failed humor is flat and leaden, but accidental humor is downright embarrassing.
Two: being ambiguous. Artfully handled ambiguity can add richness and texture and layers of meaning to your story. All accidental ambiguity does is confuse your readers, who will not be happy with you any more. And no, you can’t get away with claiming after the fact that you did it on purpose when you really didn’t, because your readers can always tell.
Three: using internal rhyme and alliteration and other sound effects. This one’s especially tricky, because the same things done well and on purpose can be wonderful. What you don’t want is for your reader to think that those rhymes (or whatever) crept in while you weren’t watching, and that you didn’t notice them.
It’s the difference between looking in control of your medium and looking like it’s too much for you to handle.