Sure, if you're going to watch it in the same mindset as you'd watch THE ROOM, I can see how you could have a good time.

"YOU ARE TEARING ME APART LISA!" = "I FUCKING LOVE ROCKS!"

You pretty much summed up how I felt about it

Yay!  Someone else is out there in the world that loved it as much as I did.  Fuck you, everybody else!

Just need a few weighting scalars on there:

Opinion of movie = (Blood Alcohol Content * Reality) - (Fanboy Level * Expectation)

Normalize that and you're good.

I don't think it works like that. If a movie is totally shit, no amount of lowered expectations are going to save it. It's more that movies you have no expectations for or have heard nothing about, that are actually pretty decent or watchable, end up being really pleasant surprises, pushing your personal opinion higher than it otherwise would be.

That was my experience watching Pandorum, where I was like "woa, this is actually a pretty interestingly thought out sci-fi story, and the production design is awesome". Objectively, it's still not a very good movie because of the stupid monsters and terrible camera-work, but if you were channel surfing and stumbled onto it without hearing anything beforehand (like I did), you end up being really impressed.

Prometheus would absolutely fit that category I think, especially because of the gorgeous visuals.