There are also things that aren't strictly scams but seem like scams and can be .massively inconvenient if you want to back track on a decision made over the phone.
About 9 years ago when I was opening my business premises, I got caught by an "energy broker" while juggling a bunch of stuff one day, who opened up by spouting stuff about the government's drive for fair and efficient energy etc etc. As I'd not yet even found out who the supplier was / had been, I thought I'd sign up to their "best deal" supplier as we were due to open soon and it needed doing.
After I'd committed, I googled said supplier and the reviews were appalling - and because it was business not domestic the 14 day thing didn't apply. So we were locked in, and having seen some of the horror stories online of random high payments etc,I refused to set up a direct debit and just paid over the phone every month which infuriated them.
All my own stupid fault, obviously, but the pitch was misleading, I was under stress, and I learned a very valuable lesson.
I hate anything that "pretends" to be a direct representative of a company you're with, like you're mobile company, and actually they're a middleman company.
I do hardly anything online if I can help it, or over the phone, and never change a thing without thorough research and if possible seeing someone face to face. I keep it as simple as possible, and if that makes me a dinosaur so be it.