I remember something that was on Nickelodeon in the early morning, during the early 2000s. So it was probably in re-runs by that time. It was a paranormal themed show. In this episode the main characters were teens (I think) exploring an old (probably abandoned) hotel. There's a scene where they are in a janitor's closet and find decades-old cleaning products. I think one was a can of Comet. And there may have been a ghost that was like a red light. I've looked into this before and couldn't find anything that matched it exactly, so maybe I'm conflating multiple similar shows.