Sixth Sense

Mechanics
The Sixth Sense skill marks nearby special enemies after standing still for 10 seconds, while the aced version cuts the penalty for civilian casualties to only 25%, making it practically a necessity when trying to stealth heists on higher difficulties without a large crew.

Strategy
Both skills are useful for stealth. With the basic, checking if there are any nearby guards helps players prepare. Aced version is for killing civilians without worrying about losing large amounts of money in heists such as R&B Bank, Diamond Store or Downtown Bank where said killing is nigh-mandatory without a full crew with aced Cable Guy.