The most disgusting thing I have seen on film

Has to be Alien Resurrection. It takes the nightmare-birth metaphors from the first movie, Alien, and makes them literally the most deformed, nightmarish creatures I can imagine. Take the alien from the first movie, with the dual head -- remember the mouth inside the mouth? Then add something approaching human/acid skin, skull-like eyes, a 4-foot long tongue, a little tiny upturned nose/horn, and you get the monster at the end of the movie -- simply stomach-turning stuff. Please don't watch the movie, but if you do, don't look for any deep meaningful stuff about the monsters inside. This movie is all about monsters on the outside.