I think the sold items reappear is probably due to return. I don't like it that if they're sold when discounted, the discount go away after they are back in stock. I do notice that if an item was returned more than two times, it gets a new marked down price most of the time.
I was eyeing a Chanel since March and after sold/back in stock twice, they marked it down by 13%. When I saw that it was included in the summer kickoff sale, I was surprised and couldn't check out faster than enough

Sadly, most of my watch items didn't make it to the 10% off list