One thing I commonly see while gaming is how common these seemingly harmless player-made programs are used for malicious acts.
Below is not an exhaustive list:
DPS meters are used to provide disinformation to change public opinions about players. It can provide the wrong measurement if whoever wrote the program seeks to alter the measurements of certain players to change public opinion about them to cause positive or negative actions to be taken against them by other players. Another way this can be used to provide disinformation is if the measurements are uploaded to a database and the data is altered by the users of the program or the data is altered by administrators of the database. These disinformation methods can be used for any variable such as damage per second measurements and animation speed measurements.
DPS meters are used to provide administrators with exclusive extra features such as giving them information about characters they normally wouldn't know in game or in-real time. It can provide information so that administrators that use the program are given information outside the scope they would know in game to evade strong players, follow players, or attack weakened players.
Surprisingly, most of the time, no one notices these things. I advise you not use these programs, as most of the time there is some ulterior motive to players writing these programs for the community and they have ulterior functions for the person who wrote the program. I advise you not to let your guard down, especially in this our community with many players who aggressively exploit everything - talking about both the NA and EU player base.