LOL - I use one of those but I also fully disassemble the locomotive. Call me anal... Or maybe I just take model locomotive servicing very seriously.
While doing what you are asking about might work to a point, it won't be perfect. For example leaving the trucks assembled will not remove the fuzz, hair, and fibers wrapped around the axles (ends and in between wheels. Even when I disassemble the trucks and use the ultrasonic cleaner, I still have to pick that stuff off with tweezers.