Someone comes along and says “I’ve discovered that there’s no need for dark matter.” A brief glance at the abstract reveals that the model violates our understanding of perturbation theory. Well, perhaps there is something subtle going on here, and our conventional understanding of perturbation theory doesn’t apply in this case. So here’s what any working theoretical cosmologist would do (even if they aren’t consciously aware that they’re doing it): they would glance at the introduction to the paper, looking for a paragraph that says “Look, we know this isn’t what you would expect from elementary perturbation theory, but here’s why that doesn’t apply in this case.” Upon not finding that paragraph, they would toss the paper away.
Yes! This is a key point in the Alternative-Science Respectability Checklist, for example: