I bought and then used four different track cleaning cars on my L-shaped layout with O-gauge O42 track and switches. The cleaning pads showed black residue, so I considered the performance(s) a success -- until I followed-up with a rag doused with 91% Isopropyl Alcohol, which removed more black residue. There's no substitute for that low tech method!
Others noted the need to clean the wheels and pick-up rollers.
Mike Mottler LCCA 12394
mottlermike10@gmail.com