When is too much targeting bad?

When it is targeting items which I have already bought.
I recently searched for and purchased a water flask on Taobao.com. Like any consumer there was a consideration phase and I took about a week to decide on the final water flask to purchase.
During that consideration period, Taobao ads were serving me water flask ads, which were targeted ads, hoping that I complete the purchase.
Now that I have made the purchase, Taobao ads kept on showing me ads related to water flasks. This is a serious case of over targeting or targeting without the right recommendation engine in place. (For one, Amazon will never re-target users in such a blind fashion).
The amount of data that is available to a brand is not huge due to the large amount of connected data across various platforms. Brand should properly leverage these data for targeting, instead of just using it for blind targeting.
How to best use Big Data for proper targeting?
1. Identify the right user group
Be it male/female, age group segmentation, browsing history, etc … identify clearly defined user groups.
2. Understand what matters to them
Determine what appeals to them, and what kind of content you can reach out to them with that will help to close the sale.
3. Follow through with the user through the purchase cycle
Follow through the purchase cycle – i.e. if still a prospect, then provide incentivised offers, if already a customer, then follow up with a loyalty program, reviews-and-get-points, cross-sell other products from different categories or based on similar users interest.
Never up-sell the same product unless you think the product life-cycle is up and the customer needs a (new) same product.