1- If you count time and wait for end instead of live moment; there is something wrong.
2- If you wear your clothes immediately after sense that indicates lack of feeling comfortable. A good sex requires feeling comfortable with your partner.
3- You think about irrelevant things during sex. That shows you can’t focus.
4- You are ashamed to talk dirty. That shows that you are hesitating what your partner thinks.
5- If you think about your previous sexual experience, there is a problem here!