Yes, there's an issue where if the ground/power pins have a poor contact (due to a bad/dirty cable or whatnot), you end up up with a short on the pin which creates tiny shocks that leave a carbon discharge, and making it drop the charge. Your phone will now create carbon discharge on any new cable, spreading the "disease" to other iOS device. Look around at any "public" lightning cable for black spots on one of the middle pins.

I think the connector is self wiping, and will eventually clear with repeated insertions.

Lightning cables are essentially consumables. I’ve spent at least two hundred dollars across our family on them. I’d rather have wireless and the efficiency hit that goes with it (in return for hardware longevity and cable cost savings).

A 5S that I bought used off ebay eventually stopped detecting the lightening port, but obviously a very old phone as I think it was within the past year that it stopped.

I'd wager that Lightning is a substantially more durable port than MicroUSB in terms of insertion cycles...

I'd agree with you, the fragility of MicroUSB was one of the reasons I wanted to change to an iPhone - I was less than happy when the android world moved on from MiniUSB