This time of year a substantial portion of our discretionary screen time is spent spending. According to a National Retail Federation survey, more than half of consumers will spread the holiday cheer this year by shopping online. Of course, you’re probably among them. And you’ve probably noticed that, in addition to an abundance of social deals, something else feels a bit different this time around: A discernable increase in the use of personalization to target content and offers.

It speaks to the maturing state of digital marketing in the retail sector, but it also draws attention to a new dynamic created by increasingly sophisticated targeted offers: The creepy factor.

What’s the difference between personalized and creepy? It’s in the eye of the beholder, which is the trouble for digital marketers today. What’s welcomed by one consumer might make another’s skin crawl.

That’s the challenge of microtargeting. Over the course of our connected daily experiences we contribute vastly to a global corpus of consumer insight based on our expressed preferences and observations of our behaviors. It makes us identifiable, not as an archetype in a market segmentation model, but as a uniquely identifiable, living, breathing spending machine human being. And with the rise of mobile computing, we’re identifiable as a point in space, like a roving wallet with a real-time geo-location.

Creepy, huh?

Well, you shouldn’t lose sight of the reality is that this data can be used for good. It can mean targeted offers that precisely intersect with the point of interest and need. It can mean better, more relevant experiences, online and off. It can mean deals on the things you actually need (and things you didn’t know you needed). And, really: who doesn’t love a deal?

I think personalization has the potential for unmistakable good—for both consumers and brands. But the question remains: how do you hew the line between personalized and downright creepy?

Comic book prophet Stan Lee told us “With great power comes great responsibility.” Key to this responsibility is adding meaningful value to every interaction by ensuring that personalization is used with care to deliver something worthwhile. Of course, this argument quickly argument turns back on itself as you’re reminded that what’s value for one is vapid for another.

Think of it this way: Your role is to be the trusted concierge that unobtrusively delivers value to your customers, not the Crazy Eddie-style deal pumper who won’t take no for an answer.

Developing a highly tuned ear for what will and won’t creep out your customers—or just plain annoy them—is a crucial skill for digital marketers. This becomes even more important as you mobilize mobile strategies; here, devices are more personal and errant messages far harder to squelch, which only raises the bar for propriety.

So, pay careful attention to the personalized experiences you have online this year and take note of which ones delight, which ones annoy and which ones simply make your skin crawl.