Westcott 16935 8-Inch Heavy-Duty Lefty Carbo-Titanium Scissors For Office and Home, Straight (16935)

There's a pair of Westcott all purpose scissors on Amazon that are great general purpose (even cutting through thick plastic packages). In the third photo, you can see the blade used by your thumb goes down. That's how you know the blades are left-handed from a pic. Took me forever to figure this out, so I thought I would share.

If they are ambidextrous scissors the blade closer to your body blocks what you're cutting. True left-handed scissors have the blade closer to you go under what you're cutting. ETA: This is a pair I have, you can see in the picture of the person cutting cardboard how you can see what you're cutting.