I have never heard of BG's anyplace I've lived dressing as FedEx or UPS guys, and driving a FedEx or UPS vehicle.
I have a cousin, however, who did have a visit from a guy who had an official looking floral delivery van - the guy turned out to have been a serial rapist, who had raped four or five women in her area by pretending to be lost, and looking for the correct address, and wanting to use the phone (this was pre-cell phone days).
Women would let the guy in to use the phone, whereupon he'd attack them.
My cousin got lucky - her german shepherd took an immediate dislike to this guy, and he took off. My cousin learned about the serial rapes later that day. She told her husband what had happened, and he insisted she call the cops. When she did, she was surprised when multiple patrol cars came; officers then told her about the other women this guy had visited.
This happened in a nice, wooded suburb of Worcester, MA, back in the 80's. Nobody would have thought to move to a nicer neighborhood, as it was in fact a nice neighborhood.
Dirtbags sometimes drive to nice neighborhoods. Sometimes, they even live in them.
Check out a sex offender registry sometime, and see who lives within a couple blocks...