In an old post I wrote on building a character, I covered the fact that there is a certain unbelievability built into plot and characters, imposed by the editors and publishers an author works with. Just because an author has met people who are that petty, that stupid...the author has seen that precise combination of unlikely events fall into place in real life does not mean the publisher or editor will find it believable.
A conglomerate author I know recently wrote a blog post about the book she has out this month. One of the earlier editors her agent sent the book to rejected it because (no kidding) "Amnesia isn't real. It's a fake thing authors add to their books to ramp up the suspense." (paraphrased from the original) The irony? The author herself suffered traumatic amnesia in which she lost a week of her life when she was a child. She has never regained those memories. The character's situation she wrote about was directly modeled on her own experiences. But the editor wouldn't consider it, because the editor's nit is a staunch belief that amnesia is not real. Or at least that amnesia as most authors without intimate knowledge of amnesia write it is not real and, therefore, it's not worth reading the whole book to see how it's been handled by an individual author.
Sadly, this editor is not alone. One particular editor recently stated on his blog that he doesn't think amnesia, autism, or Asperger's (which shows his ignorance, since that is a type of autism) are "real." In fact, he reinforced this, when he stated that Tourette's is "real," but he doesn't believe authors should use that in books either. While it's rather pathetic that these people have the power to enforce their lack of knowledge on an entire publishing line worth of readers, there's no way to stop publishers from hiring them, so you have to work within the boundaries or find a smarter editor elsewhere. I'd prefer to find a smarter editor, personally.
The problem isn't whether the author would consider it believable (unless the author is self-publishing and has no one playing gate keeper). The problem is whether the editor/publisher will consider it believable. When you've got editors turning down books because they don't believe things that are factual could happen in real life, you've got to invest in what "most" or "your average" person will think is believable. Beta readers are good for catching this type of thing, which I why (when I still used beta readers) mine were of a mixed bag of professions, places they lived, and even religions.
ALL editors/publishers (conglomerate or indie press) have their own set of "facts" and "figures" they trust are correct. I know I spend time correcting my editors when they think my facts are incorrect. Just keep a cool head while you're doing it. A sense of humor helps as well, since I've had to correct editors who believed things like...
* Women aren't allowed to have sex in the third trimester of pregnancy.
* The terms the Army uses for things are the same as the terms the Navy uses.
You can see how some of these could get amusing or frustrating, I'm sure.
Even if it gets published, the editors will be looking at these kinds of things, because readers will have the same nits.
I've worked in offices in four states (none of them NY) and NEVER had flip-flops in the office. I don't question that another author that claims to have seen it has, but I do highly suggest that the author write in a ready-made line to explain it initially, to avoid problems down the line. Ironically, I have worked in offices where steel-toed work boots or steel-toed dress shoes were par for the course, because even the office staff had to walk through the production areas, but if I write it into the story, I'd make a point of explaining it. Unless you're going to write a line explaining that it's common in that area of the country or in that particular industry (maybe the character finds it odd as well, at first glance), be prepared for someone to question you on what kind of office allows or requires such atypical office dress.
That doesn't mean the editor/publisher won't allow you to keep it in the story, but they may ask you to explain it in the text of the story. Having the line in there initially (realizing the need for such explanation) forestalls the chance that the publisher will reject the story outright without even asking you about it in editing. These sort of culture/knowledge-base clashes can be pervasive in trying to sign and put out a book with a publisher and in working with an editor. Things you know are true will be questioned and require explanation to make them "believable" to a more general audience.
You've heard the phrase "suspension of disbelief" before, I'm sure? That's not just talking about realism in writing science fiction/fantasy/paranormal/horror. It's talking about immersing the editor/publisher/reader so deeply in your story (even a contemporary story) they don't get thrown out of it by something they can't believe, even if it really exists.
One of the reasons some of the sexual gymnastics authors write don't go over well is that the readers spend half the time trying to figure out if that's physically possible or even if someone could be tied in that position for more than five minutes without cramping so badly that nothing done after it would be comfortable. Maybe the author has done the position before, but if most people can't do it, they're going to question it. Not everyone out there is a contortionist, after all.
It's one of the down sides of writing. Even if you've met people that petty, that flexible, that stupid...seen exactly that unbelievable chain of events happen in real life...that doesn't mean the editor/publisher/reader is going to believe it could happen. I'm not saying to fixate on it. I'm saying to always keep in mind that other people don't have your particular life experiences and will try to broad brush THEIR life experiences onto what they read, so taking the time to immerse them is worth the thought.