JohnLincoln:
If it was not suitable for insulating electrical joints, then it would not be called/sold as electrical tape!
I can buy all sorts of junk in the shops that simply doesn't work, eg. Ultrasonic rat/mosquito/cockroach repellants, homeopathic medicine, magnetic wrist-bands, etc.
On the electrical side there's "Cat III multimeters" which nobody should ever put anywhere near a mains socket, electrical cable with so little copper in it that it's unsafe for anything more powerful than a night light, phone chargers with fake FCC/CE markings that will probably burn your house down, etc.