Not only do the blades cover the lines of what you are cutting, but the blades are pushed together when used in the correct hand, and pulled apart when held in the incorrect hand.
For years i used the red handled Fiskars lefty scissors, then a few years ago my imgur secret Santa got me a pair of Wescott Carbo Titanium Heavy Duty Left-handed scissors and let me tell you, they are life changing! I have multiple pairs now.