Facebook already knows a lot about you. You look at a pair of shoes online one time and for the next 3 months, those shoes haunt your news feed. They constantly pop up in ad form, reminding you of that night when you decided you could pull off high-top sneakers.

If you find that common occurrence creepy, you haven’t seen anything yet. Facebook recently announced that it will start combining in-network data (what you do on a site like Facebook) with the things you do on other websites. Facebook explains it this way:

A new TV is one thing, but what happens when you buy a present for a baby shower? Will you suddenly be inundated with ads for birthing coaches and Diaper Genies?

The good news is that you’ll be able to opt out of these kinds of ads entirely. Because Facebook is adopting the industry-standard Digital Advertising Alliance behavioral advertising opt-out tool, you can simply go to: aboutads.info/choices and click to opt-out Facebook from your specific browser.

While Facebook’s new advertising tactics will be seen as smart customization by some and as a voyeuristic invasion of privacy by others, they certainly raise an interesting question. In a world where people want increasingly customized products, services and conversations with companies, how much is too much? When does it cross a line?

As you develop your marketing and work to target specific groups, keep in mind that while it’s good to know your audience, using every available detail about their lives to sell them something might not be the best approach.