A buddy of mine, who rides a '66 Bajaj Chetak (Vespa VBB clone), almost had the whole goddamn book thrown at him by a jerk cop a couple weeks ago. He only got ticketed for the speeding, though.
The claims were:
-65 in a 35
-Illegal lack of turnsignals
-Illegal lack of mirrors
-Incorrect use of collector's vehicle plate (technically, only allowed for riding to and from shows/events)
-Incorrect plate for vehicle
-Possibly illegally imported vehicle
Now, a couple of these are ridiculous. The cop said he followed my buddy from the Interstate onto a surface street, though my buddy had not been on the Interstate. His scooter cannot do 65 - even though it's kitted, it's really only capable of about 55 (thus why he wasn't on the Interstate!). It's all in the gearing. Turn signals were never equipped on this vehicle. And neither were mirrors. Bajaj didn't come up as a make in the officer's ticket system, and he had never heard of it, so he threatened that the vehicle may not even be legal.
The Collector's Vehicle plate, available in WA with permanent registration (no annual tabs) for vehicles 25+ years old, is technically only issued for vehicles which will only be driven to and from shows and events. In practice, though, this is not enforced, and there are a ton of older bikes and cars with these plates on the road every day. The cop did turn out to be correct about the plate being wrong for the vehicle, which he didn't ticket for, and my friend fixed that.
I know most scooterists aren't riding always-works-in-progress vintage Indian clones of Italian scooters and won't have to worry about all of this. But I think it certainly serves as an informative horror story... some cops really notice scooters. And don't know all the laws. And are jerks.