[lolc]

I think the proposed logic here is "a person like you buys burn cream so we advertise burn cream to people like you." In this scenario the person who actually bought the item will get the ad too.

To me, advertising a product to people who already bought it is a sound strategy. I see no contradiction. I'd rather like to hear a cogent argument as to why that is wasted effort, as is usually implied.

In your example, maybe I left the bottle of burn cream at the office. So I will want to get another one on the way home. It's effective to get reminded in my Facebook about that item (and the brand) isn't it? Yes it's creepy but it works.