I agree about checking to see if the plug is wet. However an NGK b6hs is a “hotter” plug than the b7hs the lower the Ngk number the hotter it is. (difference in electrode length)
If the plug doesn’t have any fuel on it (and if you don’t see a GOOD strong blue spark) it’s a good idea to check the carb.
Sometimes when I get a new moped I will clean and check the carb even if it starts just because it’s a simple task and carbs are very finicky. Sometimes sediment in the tank gathers at the bottom of the bowl if sitting for a long time for example. This can cause intermittent starting/ erratic running.
You’ll have to clean your carb at some point like the rest of us anyways.
Cheers and good luck