A personal story: We were playing in our team server, and the team leader came in on the other team, using a different name. I knew who it was from the intro, "SO-SO is joining the game". He used certain type styles, and had names from a common background. Before he was even in the game, I knew who it was, what his style would be, and how to counter him, while at the same time, he thought he was coming in as an unknown player. There was a definite advantage for me in that situation. All players develop patterns, my pattern is to learn the patterns of other players, and use them. It makes you far more effective if you are constantly looking at other players, and using their more effective patterns. It also gives you an advantage because you have your own habits, and the same patterns and habits as some of the top players. It makes it harder for them to figure out who you are if you come in under a different name.
Another way to effectively mask some of your patterns is to change the keyboard setup that you regularly use. If you take away a few keys, your game will change slightly. Why go through all of this trouble? Several reasons, if there is a match coming up, and you want to recon a few star players from the other team. If one player is really getting you a lot, and you want to see how he is doing it, and what patterns he is using, without letting him know what you are doing. Or, if you just want to go in and have some fun, without any players knowing it is you, and hunting you down. Learn to change your game up, and you become more effective at regular play, and in matches.