Is it safe to bake in an oven with melted plastic residue left? For space reasons, my apartment leaves some of our casserole dishes and baking trays in the oven. When my roommate went to preheat the oven one night, he failed to realize that some of them had plastic lids. As thus, it resulted in a mess of melted plastic in our oven and our whole apartment smelling awful for an hour or two. 

We cleaned it up and got it off the oven racks, and managed to scrub most of it off of the bottom. Problem is that some of it dripped down into the vent. Even upon removing the cover, I believe there's some that we just won't be able to get...and who knows how much plastic is actually dripped down there.

No one's used the oven since, but I like to bake and the holidays are coming up. Is our oven still safe to use at all? I do think it smells a little plastic-y when heated up, but it's no longer smoking...I think.
My suggestion would be to let it run at its highest temperature setting for a while (if it has a pyrolysis/heat-cleaning setting, you can also use that). Best open some windows to let the fumes escape.

When it doesn't smell and smoke any more, I would personally consider it safe to use again, especially at lower temperatures than the one you used to make it usable again.