A lot of the superficial deal-breakers
In my experience, those two films really are markers for tending to be on a certain wavelength among people in the 20-something crowd, unlike grilled cheese, ha, or other movies I love/dislike. Loving that contrived, supposedly-lovable portrait of dysfunctionality is a tired genre (when it's poorly done, it's even worse) among other things, and seems to reflect a taste/personality I tend not to click with in the long run. I mean, it's not Dane Cook-level bad taste, but something that definitely shows our heads are in two different places. You would date someone who loves Two and a Half Men or Dane Cook? More power to you. But I think it is fairly good warning for a fundamental difference in weltanschauung. I liked Forrest Gump a lot but dated someone who really hated it for whatever reason. I swear it's not arbitrary! Doesn't someone admitting they love soaps, Desperate Housewives, and the O.C. knock them down even a wee bit in your mind? Same with those two movies, but it applies to even more people, unfortunately. A hipster fellow once told me he hates people who like The Shins for some indescribable reason, even though he likes other very similar groups of equal popularity among his cohort.
BTW, I wasn't always this way; I used to be so open-minded about my partners that my brain fell out. I pay attention to those little feelings of uneasiness now instead of brushing them aside as inconsequential. In the long run, they always were tipping you off to something. Trust me. It's like how the dumb emo guy I dated would call parrots "peacocks," and it wasn't just a slip of the tongue. I tried to pretend stupid little things like that didn't matter, but they DID!
Tyro-I don't "take myself too seriously," but I genuinely tend to get on with people who have zero interest in weird, narcissistic, boring, dysfunctional celebrities. It's another marker for being on the same wavelength for more general interests. For example, they probably also won't tell me the mundane interpersonal dramas and relationship issues of mutual acquaintances because they find that stuff boring and have stuff going on in their own lives. Those two activities seem to coincide with a certain type of mindset. But I have plenty of other lame interests to make up for that preference!