Brush Type tools (Brushes, Erasers, Lassos, Stamps, Healing) Scribble in Excess with little imput.

When using any brush type of tool (Brushes, Erasers, Lassos, Stamps, Healing) that tracks the the exact path of the tool on the document it will streak across the entire document at random. 

Demonstrated below with a lasso tool the Path Highlighted in Red.