I have two axes, dividing into 4 quadrants. Both axes are labeled 'Good/Bad'.

One axis is what the film's trying to be. The other one is what it actually is.

For instance, Army of Darkness is, to me, the epitome of the Good Bad movie. It's definitely not trying to be high art, but given the opportunity, I'll watch it. Starship Troopers is another great example (although Verhoeven was arguably going for Good Good).

Apollo 13 is a Good Good movie. It's riveting, well acted, and well worth seeing.

Battelfield Earth is a Bad Bad movie. Based off of a horrible pulp Sci Fi series by a cult leader, and somehow made it worse.

Ishtar's the classic Bad Good movie. Tried to be a big, sprawling comedy with an all-star cast, ended up roughly equivalent to a dumpster fire.