I've seen many, many tragic, hysterical, or bizarre events or human choices that I'd never try to make fly in fiction. Coincidences that would really annoy and stretch a reader's imagination.
Nothing in life is "too strange" (too tragic, hysterical, bizarre etc.) to work in fiction. It can
not work, but it can also work really well--it depends on how you write it. Even coincidences, which I agree are very hard to make work in fiction, can work IF the entire book is designed in such a way that coincidences are part of the theme. Read
The House of the Spirits or
The Mermaid's Chair for examples.
As for the crazy 911 call example, with the guy's wife cuffing him to the bed and biting him, that could not work in fiction, or it could work. It wouldn't work in a Realist novel or a serious intellectual novel. If you wrote like Raymond Carver, would it work? Hell no, and I sure can't see it working in a Hemingway-style novel, either. But it would work just great if Saul Bellow wrote it (check out the INSANE characters and events in
Humboldt's Gift--I just love that book, it's unbelievably funny but touching too), or if John Irving wrote it (re-read
The World According to Garp). Which is to say, it would work great if you wrote it like Saul Bellow or John Irving; it would work great as what I think of as "deep farce"--insanely funny scenes that are also really moving portraits of human frailty and just how frigging CRAZY we are as a species.
In other words,
there is no event or character that "can't work" in fiction--but they might only work in the right kind of fiction (i.e. the genre and/or style of fiction that's right for them). Some types of characters or events are specialized: the character or event you're thinking of may only work in a magical realist novel, or a sci-fi novel, or... etc. So if beta readers are saying they don't buy a certain character, it may be that (1) the character and the story he's in aren't a good fit for each other, or (2) they are (or with a little tweaking could be) a good fit for each other, but the novel/story is not a kind that your beta readers like. For example, you could have beta readers tell you they hate a character, don't believe her, etc., but then it turns out that what's going on is you've created a romance-novel type of character, and your betas don't like romance novels, so they don't like that type of character.
In that case, you need to (1) figure out what kind of story you're really trying to write (sometimes a character may appear and drag you out of the story you think you're writing into something completely different), and then (2) make sure that you have betas who like that kind of story (otherwise the critiques they give you won't be worth much at all).