With the connector itself, it was hard to tell, but the plastic part you held in your hand (molded plastic plus strain relief) wasn't symmetrical.

You could thus develop a habit of putting, say, the flat part next to your thumb, and then you'd know the alignment of the cable. So if you knew the alignment of port, you could do reliably on the first attempt.

USB makes a slightly worse mistake, which is that the plastic part you hold in your hand feels the same way if you turn it around 180 degrees. So you have to point it at your face and look at it if you want to know which way you're holding it.