Always turning left in Unity games

This questions has come a couple of times in the last year. Both times it was a game controller plugged into the system that did not have the dead zone setup correctly.

Currently I am using a keyboard and mouse

If you are using a keyboard and mouse then why did you say "the controller always turns left, whether it be a racing game or and fps, the controller suddenly turns the player left consistently."? That's pretty confusing...

Are you sure you don't have an Xbox controller or something plugged in to your computer that is resting against something or hidden behind a pile of stuff?

Phantom Xbox controller.