Name a chat app and I can provide a link or comment from someone saying the same thing about pretty scam girls. Facebook, Whatspp, Gmail, Kik, Snapchat, Instagram, and even BBSes, AOL, IRC etc...
What I saw on FB is automatic replies from bots. What I know from Skype are african boys who try to earn their next beer in an internet cafe by acting they would be a girl. I can confirm it's all not that.