Good sales at Christmas time for a new product is not an indication of product success
Also include returns of the same product after Christmas and most importantly, sales following Christmas. If 1000 people get them as presents, but 900 return them, that's bad. If 1000 people receive them as presents, and post Christmas sales are lackluster, then the items sold well as gifts from people who thought they were nice presents, but wouldn't buy such things for themselves. Then the presents sat on a shelf and the receiver didn't spread the word because they were meh. Congratulations, your item is a pet rock. If 1000 people get them as presents and post Christmas sales show improvement, then your product will continue to sell well just by word of mouth because it's awesome. Apple is having to force these earbuds down people's throats, so I'm guessing they suck.