It's hard to know exactly what trajectory a film will take in terms of how audiences will receive it when it's completed and ready to be distributed to theaters. Many films in postproduction will endure test screenings, sure, but that's still often not an accurate measure of how well a film will actually perform, or who will resonate with it.
These days, the term "cult classic" tends to get thrown around willy-nilly, or people try to anticipate years in advance whether a recent release will one day receive such a label. But the term serves a very specific function, designating a film that gains a slow-burning fandom as the years drag on after its initial release, thus receiving reevaluation—or simply more fervent enthusiasm—from critics or fans.
Oftentimes, such films go on to become true icons of pop culture, like in the cases of "The Big Lebowski," "American Psycho," and "The Room." As the latter film proves, a cult classic doesn't necessarily have to be a good movie.
