Just clean the camera (or projector) after using any suspect film.

Any oily liquid on the film is probably the plasticizers leaching out. Another sign of degradation.

While I'm not afraid to run vinegared film, I'm not eager to do it, either. I'd try to avoid it if I could but the final decision would be based on just how far gone the film is. If it was just a little whiff of vinegar I wouldn't be so worried. If it smelled strong or had any liquid on the surface, I'd be very hesitant unless it was a "show must go on" situation like above.