no one knows exactly where the scam and what is not, except maybe he has the 6th sense may be hehe, the point back to dirikita each, we do something we really understand and we know. my advice is more careful, because it all depends what we do as well. yes so lah I never experienced it because I myself was not careful.
Yes you are right, you can easily determine if the people you are talking to is intending to scam you or not just by looking at the gestures so its easy to avoid those people who are really insisting to sell to you some coins or asking you to invest on their ico. The only unavoidable thing is being hacked from phishing sites or to reveal your self recklessly and that will be a big problem for you.