Corporate manipulation. Almost every rated product has all 5 star ratings. You submit reviews for points towards free shipping. they "reject" them and revoke points, but your reviews stay live?!? You spend days checking in to earn 100% off shipping only to find out you can't use coupons on flash sale items. You remove them and spend time shopping for new items only to find "100% off shipping" is capped at $20, so you'll still have to pay 30+% of the purchase cost in shipping!?!