Starting soon, we will be experimenting with a way to make ads on Twitter more useful to our users in the United States by displaying promoted content from brands and businesses they’ve shown interest in. Users won’t see more ads on Twitter, but they may see better ones.Twitter Experiments With Better User Control Over Tailored Ads [blog.twitter.com]
While we want to make our ads more useful, we also want to give users simple and meaningful privacy options. Simply uncheck the box next to “Promoted content” in your account settings, and Twitter will not match your account to information shared by our ad partners for tailoring ads. This is the only place you’ll need to disable this feature on Twitter.
And because Twitter supports Do Not Track (DNT), Twitter will not receive browser-related information from our ad partners for tailoring ads if users have DNT enabled in their browser.
It's about time someone started respecting DNT. Just to be on the safe side I went into the profiles of all my accounts and turned off the ad tailoring as I'm not always on Twitter with a device/browser that lets me set the DNT option.