To be fair, "Catfishing" is extremely common. I've known multiple people who were talking to somebody online and I hated to tell them, but I could tell right off the bat that the chick in the photo wasn't who they were talking to.
Just being honest and realistic, at this exact moment, a big majority of hot girls on the Internet that guys are talking to, without having ever met, are Catfish. It's a really common thing. People enjoy living a fantasy life online.
I've even been messaged a few times on here by really hot girls with no Verification Photo (I've also seen a few Verification Photos on here, where it looked like the screen name had been Photoshopped into the picture).
There are usually some easy signs to pick up on, if you're looking for it. Not to sound shallow, but you have to really be self aware about whether your level of attractiveness (both physically, and the way that you present yourself online) is on par with the person you're talking to. And also if your own profile has enough information or personality to it, that it seems reasonable that an attractive female would be interested, based just on that.
Having said that, I have known very quality girls who are a bit quiet or shy (my type), who have talked about having done online dating, and I thought "Holy shit, if I knew there were girls like you on there, I need to sign up!"
Idk about just messaging random guys who they've never met. I'd definitely be cautiously optimistic, at best, in that scenario. I've been hit up before, out of nowhere, on Facebook, by a girl who I hadn't seen since Middle School. She had a crush on me back then, and I guess just thought about me one day and decided to give it a shot. Lol, turned out to be having an affair on her boyfriend with me, unbeknownst to me, but still, that kinda thing can happen.
There are definitely easy ways to prove they are who they say