Where there is competition, there will be cheating.
In baseball, there are ways one can apply the word "cheating" and have it not be construed as a bad thing. For example, as Merriam-Websters dictionary defines it: "to position oneself defensively near a particular area in anticipation of a play in that area." As an example: "The shortstop was cheating toward second base."
A batter can "cheat" on a pitch, meaning that he can be anticipating a certain pitch and start his swing prematurely.
Then there is the actual negative connotation of the word.
Throughout the history of the game, there have been players that have been accused and found guilty of breaking the rules of the game for their own competitive advantage. Everything from corked bats, doctoring baseballs and, yes, even steroids have come to pass.
Here is a look at every MLB team's biggest cheater in team history.