Are gas scooters illegal to ride in California?

No, of course not, that is ludicrous. HOWEVER, a 49 cc scooter has a maximum speed of 30 mph, so it would be illegal to ride it on the freeway, it is a city transport only.

Yes. I see folks (kids wearing helmets included, so it's not a helmet thing) get pulled over all the time with them. They are noisy, polluting, and unsafe.

anything is legal... as long as you dont get caught ;)