When writing with your left hand you end up dragging your hand over what you just wrote which will smudge if the ink is still wet. I think it's saying that the quick drying part makes it a better ink for the left handed.

If these are for fountain pens, as they appear to be, the pens an absolute bitch for lefties to write with. Some people turn the notebook almost sideways to write in order to avoid the smear. Justified product for sure.

Did you find this at The Leftorium? This is the ink Ned says that smells good?