Why is smoking an unsociable practice?

Answer 1

Most people don't smoke. If you smoke around those people they will consider you unfriendly.

Many people consider the smell of burning tobacco noxious and intrusive. As the nature of burning anything is that it moves as the air carries it, the act of smoking becomes intrusive.

Look at it this way: if you had a conversation with a friend and he posted himself six inches from your face as he spoke to you, you would feel he was invading your "space." Now, make that friend a stranger, and what before was uncomfortable becomes potentially a threat. That's how others perceive smoking.