1. They are very negative.
2. They blame everyone else for their problems.
3. They find something wrong with you and everything you do i.e. very critical of others.
4. Expect others to make them happy and support them.
5. They are very jealous if they perceive you have something they don't, even if you worked hard for it, that doesn't matter to them. They don't appreciate your hard work and sacrifices to make your dreams come true. They will probably get ticked off and hate you for it.
It's probably best not to be around these kinds of people if at all possible. I personally think people like this are bad for my well being.