The only real difference that matters between a fake site and a real site is that the information on it is genuine, the form doesn't really factor into it. Which makes this a very tricky problem: You can't tell if the data is genuine before you have the genuine data.
If you're trying to do something for the first time with a big company, you usually know the domain name. Like Google is google.com. Or for something like your bank, it'll be printed on your credit card.
