Okay, to expand: boring in the sense of not being engaging or providing you with something to think or talk about. For example, a movie with a predictable plot, static characters, and stilted dialogue. Compare that to a movie with a many plot holes and hammy over-acting. Neither would be 'good' movies objectively, but the latter would have something you could be engaged in, perhaps for the novelty and strangeness of it or the unpredictability (of because it provides more fodder for you to ridicule it with).
The theory is that there are bad things out there, but some fall into the "so bad it's good" category for whatever reason appeals to you, and that a boring movie isn't even bad enough to be worth your time.