What makes a bad horror movie?
The main purpose of any such list, of course, is to get people arguing. Judging by the comments with some of the listings, I don't think "Editor" has actually seen all of the films in question and picked some them for their titles as much as their poor quality.
I haven't seen all the films on the list, have never even heard of some of them, but I don't think some of them belong on the list.
Some were intended to be at least semi-funny, such as "Attack of the Killer Tomatoes" and "Killer Klowns from Outer Space." I don't say they necessarily succeed, but the list isn't "10 worst comedies."
I could also argue that several could probably fall in the science fiction category too, but there's a long tradition of horror films with science fiction trappings.
One, "Plan 9 from Outer Space," is such a classic bad film that it was even voted the worst film of all time in "The Golden Turkey Awards." But in Dan Peary's "Cult Movies," he argues that although it is incompetently made with no-talent actors and no budget, it is a far more subversive film than generally credited and thus far better than the worst film of all time. I'd actually prefer to watch Ed Wood's masterpiece than some more recent bigger budgeted films.
The one film I most vehemently disagree with including on this list is "The Howling III: The Marsupials." Unlike "Editor," I've actually seen the film. It's not a perfect film by any means but it is at least half satirical and at times serious minded. It's not even the worst film in "The Howling" series (which includes "The Howling II: My Sister is a Werewolf," in which werewolves are dispatched not with silver but titanium and B-movie actress Sybil Danning repeatedly rips off her top, and "The Howling IV: The Original Nightmare," a new version of the excellent first film in the series, only without any of the qualities ~ a script by John Sayles, direction by Joe Dante, talented actors ~ that made the first film successful and spawned the series).
I'd guess it's the "marsupials" part that put the film on the list, and that's probably all down to the director being Australian and thinking it was a novel twist. The film treats lycanthropy not as a disease that can be spread but as a separate evolutionary path. It opens with an anthropologist uncovering evidence of werewolves and an old film of one being burned at the stake. One of the protagonists is a young female werewolf who runs away from her tribe to try to live a normal life. Ironically, she's spotted by a film director (a caricature of Alfred Hitchcock) and cast in a horror movie. She's pursued, which results in werewolves being outed and, eventually, assimilated. It's a little disjointed, veering from comedy to horror, but I liked it.
The bad movie list phenomenon went big time with the release of "The 50 Worst Films of All Time" and its semi-sequels, but I much prefer the approach of Michael J. Weldon in his defunct "Psychotronic" magazines and the out-of-print books "The Psychotronic Encyclopedia of Film" (1987) and "The Psychotronic Video Guide" (1996). They're badly in need of reprint and update. Weldon embraced the quirkiness of films that most would consider simply "bad." If you're interested, I think Book Beat in Oak Park may still have some remaindered copies of the "Video Guide."