I can’t speak for anyone else posting here, but I tend to view a crap movie as any movie where any of the flaws you mentioned interfere with my enjoyment of the movie as a whole. That doesn’t mean that a movie can’t be enjoyable in spite of its flaw. Nor that a movie I call ‘crap’ won’t excell in certain aspects of cinematography.
As an example, let me go back to Adventures in Babysitting. It was written and played as unabashed cheese, I believe. It starts with a mundane situation, and goes surreal with high speed. The acting is pretty good, the script carries off the situations so that the audience gets carried along beyond the more outrageous points without too many ‘speed bumps’ and provides an enjoyable show.
It’s also a movie that must go quickly, because if the audience is ever allowed a chance to think about the story the bs flags will start flying. And that single glaring flaw, in my opinion, keeps it from being anything but a guilty pleasure.
Perhaps instead of using the term ‘crap’ for these films ‘guilty pleasure’ should be substituted, instead. Note, also, I’m making a distinction between whether I enjoyed a film, or whether I think it’s a good film. I can speak to any number of excellent films that I really didn’t enjoy, including Animal House and Porky’s. But that’s not because they’re comedies or such, just that they don’t speak to my particular tastes.
Nor do I think that film must be a drama to be considered a good film. To continue with the genre of surreal comedies, let me suggest the Cary Grant film, I Was a Male War Bride. (A film I reccomend to all viewers, btw.) Now, much of the surreal nature of the film is based on something I find completely believable, i.e. military regulations chewing up some poor slob. That may make me able to accept the piling up of surreal factors that I can’t accept in Adventures. But there are only one or two coincidences that are required in the plot to keep it moving. Rather the surreal aspects come from people (and regulations having been written) having the assumption that all military bringing back a spouse from Europe would be men, bringing back wives.
If I may paraphrase something I said in a thread recently touching on judicial matters: I can accept a single coincidence in a plot without a hiccough; when they start piling on, especially in a manner that is necessary to continue the plot evolution, my suspension of disbelief gets weaker and weaker with each added signifigant coincidence.