For example, if someone pretended to be a woman (who doesn't actually exist) on an a chat site, and they use an artificially produced profile picture of a woman, or anime character or something. Then they tell the person to sign up to a cam site (affiliate site) to watch their cam, would this be illegal? If so, what law would be being broken?
depends if they get the service they wanted from the site they sign up with... if its just fake they will charge it back via their credit card company
Fraud. You're talking about fraud. There's the name of the crime you were looking for. You're welcome.
The thing about the question you're asking is that you don't specify the country whose laws you are worried about. Now, I can see you're in the UK but it would be better to give that information upfront. But you might be worried about future plans to travel to the US or Europe if there are outstanding warrants for your arrest. If you talked to a real lawyer you'd probably be mocked for using an online forum to check legal details. Better to ask someone who can give you a professional opinion and defend you if you ever come unstuck. If you think about it logically you are receiving funds by deception. Does that sound like something that should be legal? Does it sound like something you can talk about over Sunday Dinner with your parents? Does it sound like something you'd mention to someone you're hoping to have a relationship with? I'm big on being open and honest and I'm guessing you couldn't be open and honest about your ewhoring operations.