It depends on what you count as nice, can you be nice to spammers?
You can be nice to spammers too. Be nice to their personality and report their acts to the moderators or whoever in charge. Also you can use the ignore tool without being harsh too.
Not everybody you can be nice too, if you are always having a quality post, you will be nice to people that have quality posts, not spammers. Haven't you seen a very good poster correcting newbie and the newbies said no it is not like that when the newbie is blatantly wrong.
Niceness and respect is backward compatibility.
It does not mean that the higher will always be nice to the lower. In the above instance, it means that the newbie is not being nice to the person correcting him
This is a forum with plenty people, people can not and can never act the same or be the same but the best way for people to show kindness to you is to act like they are, if they post good, you too post good to draw their attention.
Kindness has nothing/little to do with quality of post.
4. Being nice will earn you more friends and admirers.
2. Respect the privacy of the forum users by not sharing their details or data without thier consent.
Information you told a person, many people could have heard it even after you trust the person that you told. You can be visiting this forum with tor or vpn and remain anonymous if you want to be anonymous, if you have told someone about you here, then expect many other people to have known you.
Privacy especially in this context is not all about identity.