I’ve always been around a lot of people. Some were good and some were bad, or a little bit of both.
First, when you meet someone check out his or her smile. If it is a wide smile with teeth showing, then they are most likely a sincere person.
Second, when you get to know them try to figure out what they are into; like their interests. If you notice that person talking badly about others and then you see them being nice to the other person, their obviously a fake.
Lastly, do not put your guard down. Make sure you really know the person before you put down the slightest bit of your guard down. Believe me I know how most people work. My saying is expect the unexpected.
I hope this helps you out.
Thanks, take care, and peace.