Reputation is the opinion of the public towards a person, a group of people, or an organization. It is an important factor in many fields, such as business, online communities or social status.

Your reputation is the sum of all the ideas that people have about you. Just as you do not own your name, so you do not own your reputation. If the opposite were true, then you would own the ideas that people have in their heads, which is absurd. Thus, you have no right to a good or bad reputation. The only thing you can do about your reputation is to change how you act.

When you do something, other people develop an idea of you in their heads. If you grief, then they associete your name with griefing. If you appear to be griefing, then they still associate your name with griefing. Reputation is about perception; reputation is not necessarily dependent upon reality, though reality does play an important role.

Just because you want people to think of you differently on a test server does not mean that people are going to think of you differently. If I were to team up with a griefer group on the CivTest server, then my reputation on the Civcraft server would be tarnished greatly. This is a contributing reason why I do not grief at all: I do not control my reputation, but I can at least try avoid getting a bad reputation by simply not griefing.

What you want does not necessarily make reality so. You have to act in the proper ways to achieve what you want.