I will sum it up in one word. Compassion..
When you have compassion one will even treat mad dog with thoughtfulness. Communication is the key to success, compassion is the key how you treat a person, including an animal.
I think nice guys are those that are respectful, good communicators, thoughtful, generous, emotionally available, and gentlemen. But don't mistake us nice guys for wimps. I consider myself to be quite strong and quite passionate in a relationship. I just prefer to save it for one woman and not seek to take advantage of others.