[quote=@Rapid Reader]
If a person has anything by Jordan Peterson on their bookshelf.
[/quote]

[quote=@Angry Ariel]
I came here to say Jordan Peterson, too, lol.
[/quote]
Man, you two would hate the millions of other general self-help books that get published every year.[hr]
So because I know most readers will own a wide variety of books and novels, whether they actually liked them or not. (Political, spiritual and historical minds, especially.) There's not too many books that I can imagine getting that kind of immediate negative reaction from me. With one potential exception...(And even then, I know people can gift you bad books as a joke sometimes. So...)

[s]Oh, wait. I just realized that most previous answers had failed to meet the proper context of that question. So I wrote this by proxy. Though now I realize the question wasn't "what book would make you judge a person's character, if you merely saw this in their possession." And that it was someone fondly gushing over the work in question. So my answer is even more certain. Because I refuse to believe that any rational person would include these in their favorites.[/s]

My answer: A modern president's or career politician's autobiography or novel. (Take your pick, it probably applies.)

Because I can't actually think of a pragmatic reason to buy that, aside from a celebrity-esque worship of that particular figure. Since one, you're learning fuck all. (Nothing the internet couldn't tell you, at the very least.) Two, you're supporting a ghostwriter and are probably the kind of person whose unaware of that. Third, I can't think of a more boring and pretentious self-indulgence, than having to read about a professional bullsh*t artist and how they'll be fabricating their own past to me. 

So in conclusion, you probably won't get any funny or good writing out of it. There will be no interesting styles or subject matter, that most fiction provides. You learn nothing, in comparison to other better political or historical literature. Nor will you be able to improve yourself, assuming you take it as life advice. ([s]And you can't even fap to it—or hell maybe that IS the demographic who buys it. I don't know.[/s])

[i]I digress. If you want to show your political affiliation that badly. Just get a funny t-shirt or something.[/i]