Any way to get a clean Reputation on XBL?

Solution 1:

You could always try to balance your reputation by playing games with a cooperative focus, or team-based shooters such as Team Fortress 2 and Left 4 Dead. You receive a lot of friend invites in games like these which you can turn into positive reviews fairly easily. Otherwise, if you continue to play fighting games, you can try to offer helpful advice to players you beat or congratulations to players who beat you.

For completeness, the Xbox 360 player review system works like this: You can either prefer a player or choose a reason that a player is to be avoided. Those reasons fall into three categories: Communication, Game Behavior, and Player Skill. Bad reviews for Player skill do not affect your reputation (although being reported for being `too good' is hardly a bad thing) so we will ignore them. Of the others you will want to avoid Trash Talking, Unpleasant Language, and having a Disruptive Voice. You said that you didn't use a microphone, so most of these do not apply to you, but mic users should turn off their microphone when not in use and make sure it is functioning properly as to not create static and you will want to edit any comments you feel the need to make after a match.

Your negative game behavior can also be marked as Overly Aggressive, Unsporting Conduct or Quit Early. Play until the end, don't cheat, and show the other players that its all in the name of fun every once in a while to avoid tags like these.