Its scab, caused by a small soil organism. Potatoes are still good to eat when peeled. Acidifying the soil would probably help as scab is worse in alkaline soils.

yes it does sound like scab. the skin gets a 'corky' blemish. but as said still fine to eat [peeled/scraped or not!] and less likely on less alkaline soils.

Quite right Stera and SBG. We used to put the first grass cuttings into the potato trench to make it more acidic.