Some brushed motors don't have neutral timing. As such, they will consume less current and run more efficiently in the marked direction. I wouldn't run a brushed motor against its preferred direction for very long. It will generate a lot of arcing inside, wear the brushes and worst can destroy the controller. Thats my experience from RC motors and I would think it also applies to ebikes/scooters.
You can tell by doing the following experiment.
With leads connect straight to the battery insert a current meter in series with the motor. Let the motor spin and get to its max speed. Now flip the polarity. If the measured current is the same in either direction then it is neutrally timed and doesn't have a preferred direction. If it consumes less current in one polarity, this is the preferred direction and the direction you want it to pull you forward.