Terrible Potatoes Sold As Class 1

I've bought several bags of potatoes on different occasions. On the outside, the potatoes are marked as class 1. This points to a good quality potato. But for the last few bags I've bought - at an expensive price - the potatoes were always subpar. Some were rotten, others were "moer" potatoes that barely soften no matter how much you boil them. But the worst I've found in several bags now is that nearly all the potatoes have black cores. This is disgusting considering the price and the supposed class 1. Clearly the class 1 grading is a sales gimmick. Very disappointed.