That's the best way to see how many services still relies on http at least partially.
... unfortunately
I hope it will get better and soon we all will be able to do that
I’d argue people who are thinking of using a VPN wouldn’t fall for this kind of attack.
What signs should the user be paying attention to?
The attacker cannot serve to the victim a valid certificate for facebook.com unless the facebook.com private key or a CA has been compromised.
Alternatively the attacker could try a close enough domain (facebooks.com, or something) that it controls and for which it can get valid certificates, and redirect the victim hoping the user won't notice the slight difference in domain name.