[rwl4]

Whoa! I remember experiencing this and just assuming it must be my imagination! I also remember that same laptop getting those pits. No where as dramatic as the pictures in the linked page, but still pronounced. Crazy.

It's never happened to my more recent MBPs.

[wkat4242]

All my more recent alu macbook did the same. I can feel the roughness as soon as it's plugged in. If you rub over it with a hand you feel this 'friction'. It's hard to explain.

You can also measure it by the way. It's significant voltage but can't sustain any current of any kind. My hypothesis was that it's some minor induction from the PSU transformer being picked up by the shielding and transferred to the laptop through the ground wire.

But the pitting, no. But I never got that back in the day with my 15" PowerBook either. I mustn't have the right chemistry.

I'm just saying that if you have the pitting, using a grounded socket might make the chemistry different in a way that it causes this less. Putting an electric charge on metal is used to prevent corrosion in underground fuel tanks for example, but it can do the opposite too. Ships do it too but they usually use 'sacrificial metals' to transfer the corrosion to.

PS: I don't know the correct English terminology for the above because when I did chemistry it was a long time ago and in Dutch.