We first try to decide what type of device it is based on capabilities (e.g. if it has switch and color control we can be fairly certain it is a light bulb) and then DTH name. However, this obviously wont work if it is a generic zigbee switch for example since we don’t know if that is a switch, an outlet or what is connected to the device (light, fan etc). Hence, we fallback on device name as you guys have already figured out trying to see primarily if it is a light or not, and possibly if it is an outlet.
Now both Google and Amazon allow you to change a device to a light which is basically the only safe way since only the owner of the device will know what it ultimately represents. This feature would be useful to add to the SmartThings app as well.