The Worst Movie Of All Time

What is the worst movie of all time? Plan 9 From Outer Space (1959) is often thrown around, but what about Isthar (1987) or Sgt. Pepper's Lonely Hearts Club Band (1978)? There were people who loved those movies just as much as the people who praise The Godfather Trilogy or Citizen Kane. What exactly makes a bad movie?

Is it the production values? Bad dialogue? A plot that has been rehashed over and over again? No chemistry among the lead actors? Plodding direction? Poor acting? Too many special effects, car chases or gore?

Sometimes a movie that was judged to be bad upon its release is declared a classic years later. It happened to The Wizard Of Oz (1939). Then you see something that won multiple Academy Awards back in the day and wonder, "Why in the world did anyone think that was good?"

Are movies well done because the critics say so? Some movies that Roger Ebert gave thumbs up to, I thumbed my nose at.

Are American movies better than foreign films? If a movie is animated, does that mean it is automatically not better than a live-action film?

Is it just a matter of audience members personal tastes?