While brands have long used artificial intelligence and machine learning to customize ads, personalization powered by generative AI is uncovering new obstacles for marketers. The issue at hand: When does personal cross over to creepy? A piece in AdExchanger look at how personalization can go right—and how it can go terribly wrong.

“While brands have long used machine learning to generate thousands of customized variations of retargeting ads and copy tweaks, personalization powered by generative AI is creating new challenges for brands,” writes AdExchanger‘s Hana Yoo. “For instance, generative AI tools can theoretically generate thousands of complex variations of creative in a day. AI can also tailor creative copy or suggest products based on individual preferences and behavior, which consumers may find off-putting–either because the personalization attempts are off-base or because they are uncannily accurate.”

Here are real-world examples of personalization tactics that miss the mark and those that are successful.