Which is worse: The fact that the National Security Agency worked with tech companies to track unknowing Americans? Or that advertisers like spamming customers' email accounts with so-called relevant ads? According to a surprising new study, it might be the former. 

Pew found that 28 percent of American Internet users try to hide their identities and online activities from advertisers, while only 5 percent try to avoid Uncle Sam. Obviously, Americans want to hide from hackers or criminals, who comprise the largest group they hope to avoid (see chart). 


Of the 792 American adults Pew surveyed, 86 percent said they cover their tracks by employing one (or more) of the following tactics: clearing their Internet browser, deleting posts on social media, using virtual networks to conceal their IP addresses, and/or encrypting their data. 

That more Americans are concerned about the wealth of personal data floating online isn't suprising. In 2009, only 33 percent were worried--now it's 50 percent. But with more companies using relevant advertising--that is, targeted ads based on what sites users are browsing, what they type over email, and what they purchase online--that concern may worsen. 

To wit, sixty-eight percent of those surveyed said the content of their emails was "very important" to them, while 62 were concerened that the names of people they exchange emails with or mention in passing may become public. 

As more consumers install ad-blockers, marketers will need to walk the line between being "relevant" and respectful. After all, what good is a targeted ad if it only scares away your customer?