Jabootu's term) I enjoy movies at "the bottom of the Cinematic Bell Curve". This doesn't mean that I don't also like good movies, just that I enjoy movies that differ wildly in quality.
Most B-movie fans have a single basic requirement of their movies; the movie must entertain them. If that entertainment comes in the form of unintentional laughter, then so be it. Thus, the worst sin a movie can commit (aside from being immoral, of course) is to be boring. This is why few B-movie fans tolerate bad comedies; bad comedies, by definition, are neither funny nor entertaining.
For many people I know, Battlefield Earth (I'll just abbreviate it as BE) is the worst movie they've ever seen. You may remember BE as John Travolta's pet project; a science fiction movie based on the book by Scientology founder L. Ron Hubbard. The movie takes place in the year 3000 AD when humanity is entering its thousandth year or so of being enslaved by an evil alien race called the Psychlos. Travolta himself plays the primary villain, Terl, the Psychlo head of security. A human named Johnny decides to lead a rebellion to rid earth of the invaders. The movie is full of plot holes, it's filmed using bizarre camera angles and set lighting, the story is dependent on outrageous coincidences, and the dialogue and acting are ridiculous. The Psychlos are meant to represent an intimidating and brutal alien force, similar to Star Trek's Klingons (the Psychlos' language, costumes, and makeup even resemble those of the Klingons). However, their ultra-capitalistic, back-stabbing, profit-driven society more closely resembles that of Star Trek's Ferengi. At least Star Trek realized that the Ferengi were an absurd caricature and played them for laughs.
I didn't get around to seeing BE until this week (thank you, Netflix instant viewing!). So, what was my initial response to BE? To borrow the B-Masters tagline; "Meh. I've seen worse". I was actually disappointed that it wasn't as bad as I had been told. Heck, just this past week I watched The Skydivers, The Final Sacrifice, and The Bloodwaters of Dr. Z, all of which were significantly worse than BE. Unlike those other movies, BE met my most basic requirement; i.e., it kept me entertained the whole time. In addition, if you look really hard, you can actually see that BE could have been a good movie. It reminds me of the Batman franchise; in the hands of a hack director, with a lousy script, and constant outside interference (Travolta and his Scientology gang in the case of BE), you get truly disappointing movies like 1997's Batman and Robin. However, with the right movie-making elements you can get a great movie like 2008's The Dark Knight.