That's what he says, but they lack the skepticism of actual scientists. I love the movie - and the quote - but Venkman is clearly calling himself a scientist because it's convenient at the moment.

Wait, how do we know that Venkman isn't a legitimate scientist, again? Because he's insufficiently skeptical about ghosts? But in the universe of Ghostbusters ghosts physically exist!

If anything, the part of Ghostbusters that strains my credulity is that in their universe there seem to be scientists who don't believe in ghosts. You'd think that the accumulated evidence would be pretty overwhelming by the 1980s!

IIRC, the spate of hauntings in the movie was brought on by the imminent return of Gozer the Gozerian (or by the same rare set of conditions that allowed Gozer to return).

By the sequel, the Ghostbusters had mostly closed up shop due to the collapse of the haunting bubble.

I was thinking more of that scene, where his line before that one was "Are you, Alice, menstruating right now?" It's clear he's more interest in her than the study. Again, it makes for a funny movie, but it's also making fun of scientists.