I used to play with a notorious TF1 sniper who constantly got cheating accusations. Saw them play live once, and they were just that good. But with a catch - they lowered screen resolution to the absolute minimum, meaning higher refresh rates, and bigger pixels. Bigger pixels meant easier head shots, as if a bullet path hit a bounding box, the rendered pixels of the target were then used to determine hit/miss and hit location. They also adjusted their screen contrast making everything look awful, but apparently easier to make out the important details.