I think that scam is particularly effective because they use gotomeeting, or similar software, to remotely control the victim's PC and then actually go through

I think that scam is particularly effective because they use gotomeeting, or similar software, to remotely control the victim's PC and then actually go through a scripted tech support session eventually running phony antivirus software which displays to the victim that there is a plethora of viruses/trojans/malware installed on the PC. For someone who has never had someone remotely control their PC, they most definitely seem like legitimate Microsoft tech support agents. I would imagine that would fool the vast majority of people sadly.