Hi Zobel,
That is one way to know if we are really chatting with the person we know. If he/she keeps on answering in tagalog whilst you were using the Bicol dialect then that's for sure he/she is a different person but how about if the chat between two persons is accurate as to the persons they both know and their whereabouts?
Yeah i agree with you Sophie, there's a lot of ways to figure out if you are chatting with your friend or a hacker. In Zobel's case the person was inviting her to flickr acct and can't understand her dialect and your friend was borrowing money which you said is doubtful for she is not that badly in need. So we have an instinct, we can feel that something's wrong.