After reading Raw Danger's excellent post and the discussion it generated, then seeing io9's Charlie Jane Anders tackle the same issue, I decided I'd like to make a few points that are, frankly, too pretentious and verbose for any standard comments section to handle. Hold onto your butts.
Raw Danger asks us a fascinating question: does having to actually engage with a piece of terrible art make it a worse experience, or a better one? Does the act of pressing buttons improve upon a mediocre game? Or does it harm it, by shoving your nose in the unpleasant experience? These are great questions, and personally I think they can only be answered on a game-by-game, and indeed, a player-by-player basis. However, one point that was widely agreed upon was the crowd factor. Playing a terrible game among your friends and loved ones can be a truly joyful experience. Play the same game alone and you might end up in a controller-hurling rage.
io9's post, on the other hand, attempts to create a series of guidelines for these kinds of experiences in film. It begins by conflating midnight movies, cult classics, guilty pleasures, and the "good-bad" all into a single category, doing nothing to distinguish these types of experiences. Anders' list of factors to consider is certainly a valid point of view (indeed, one can measure any movie by them, regardless of its critical status), but it doesn't exactly illuminate the question of why we enjoy these types of experiences; it only obscures it further.
What Anders describes is a love of schlock, not "good-bad" movies.
She has a point: January is the month of schlock, and this year's batch looks... well, it looks remarkably like some other schlock we've seen before. But personal preferences aside, to consider The Rocky Horror Picture Show, and last year's already-forgotten supernatural action flick Legion as operating on the same level of appeal seems, frankly, absurd.
Truly "good-bad" movies need something far more special than a few winking jokes, an unserious plot, and a crapton of CGI. Don't get me wrong, I have been known to absolutely love some good schlock (I'd put Dredd in that category, for a recent example), but let's make some distinctions here. For simplicity's sake, I'm only going to talk about schlock vs. the "good-bad" (and ugly).
Lost in Translation
"Good-bad" movies should ideally be made outside the studio system, or at least by an outsider. The gap between "what the film intends to do" and "how the audience receives it" should be not a mere gap, but a veritable Marianas Trench so as to render the filmmakers' intentions completely alien. One reason Birdemic works so well is because of the "Shock and Terror" subtitle. Someone made a conscious decision to illustrate the idea of "Shock and Terror" using the medium of film, and fucking Birdemic was what they came up with. That's pretty hilarious.
The prevalence of non-native English speakers as directors of these movies is hardly a coincidence. Some barely even bother learning the language (Troll 2), and their films are awash in oddball cultural mistranslations ("having a catch" in The Room).
But these would be rather hollow (not to mention, cruel) experiences if all we had to go on was a director's inability to communicate.
Playing to the Crowd
As mentioned earlier, group participation can be key to the enjoyment of this kind of art. This can be as simple as having a good group of friends, or as complex as the ritualistic midnight-showings of Rocky Horror. The key to this aspect is taking the experience outside of the movie itself, and putting it in a different context that it's more suited for.
I first watched The Rocky Horror Picture Show alone back when I was in high school, knowing nothing about it other than that it was regarded highly among my friends. The experience was utterly baffling. Years later in college I went to a midnight showing, and the difference simply cannot be overstated. In this environment, you can almost imagine the group of people who first saw something special in this funky little musical, and gradually kept letting more and more people in on the joke until it became a true underground phenomenon.
ETA: And while Rocky Horror doesn't fit neatly into any of these other criteria, it does provide a useful example of cult-fandom.
Chances are, if you saw The Room, you were shown it by a friend. Maybe you were the friend who showed it. But this act of taking someone aside and saying "you've gotta watch this" is a film's first step towards cult-status.
The "It" Factor
This aspect is a bit tricky to pin down, but put simply, it represents the artist's passion, joy, and commitment to the project.
Perhaps nothing else will endear me towards a movie more than the palpable sense that these people are having fun. This is an absolutely crucial distinction between schlock and the "good-bad." Hansel and Gretel, for all it's winking little jokes and zippy pace, feels like a slog. I cannot pull recognizable human emotions out of it; all I see are special effects and quips. This ties back into the first point; someone who's independently financed their own film is going to care a hell of a lot more than someone who's agent simply got them another job.
Best Worst Movie, the documentary about Troll 2, hits on this point excellently. Rough spots that would be sanded-over in the traditional studio process are instead left behind, revealing more about the people who made it than they ever probably intended. The difference between slickly-packaged entertainment and the project-of-passion isn't always manifested in the objective "quality" of the final product, as much as I personally would like to believe that passion trumps skill. And yet, regardless of "quality," the differences between these two approaches are very significant.
The combination of technical ineptitude and passion is a heady mixture. You throw in some good friends, and you've got a recipe for some of the best movie-watching experiences I've ever had.
Now everyone go watch Miami Connection.
A few final points:
These criteria are meant as jumping-off points for discussion, not the final word, so I welcome any criticisms. Also, I didn't really talk about video games (sorry Raw Danger!), but that's mainly because I think there's a whole other set of factors to consider on those. And finally, I didn't quite get around to defining "schlock," so here we go: schlock is simply unpretentious entertainment. It's a rejection of "high-art" concerns, instead focused on the superficial aspects of its enjoyment (very similar to "kitsch" in the art world). Ambition is the death of schlock, but the "good-bad" needs it. It wouldn't be "good-bad" if the ambition hadn't outstripped the technical ability somewhere along the way.