You are correct, some people are insensitive & judgmental & often mean. People like that are insecure & lack confidence & don't feel very good about themselves. So keep that in mind & you will feel sorry for them instead of thinking they are mean. Don't respond to negative behavior or comments from others, it they don't get a response from you they will eventually stop negative behavior & comments towards you. Don't take things personally when people treat you badly, it's their problem not yours. Ignore bad behavior. There isn't anything wrong with being serious, but it's a good idea to smile & appear happy. When in doubt about what to say, listen carefully & ask questions. Be interested in others. Arguing or correcting others will not help you or get you what you want even if they are wrong. Being a right fighter only benefits you if its for TV, it never benefits relationships whether they be personal or work. Less is more. Listen more, talk less. If you don't understand something, it's ok to repeat it back & ask for more clarification so you understand. Compliment others, but it needs to be genuine. From the very first moment to see someone look for things you like. It could be a sweater they are wearing, a clean organized desk, useful information they provided, and so on. It's hard for people to be mean to someone who is genuinely nice to them.