I use an ad blocker and DDG, but I still see ads when I search for something. The ads appear like Google search ads, but clearly labeled, so I doubt my ad blocker is going to be able to detect them without a feature to specifically target DDG.
I don't have a problem with those ads, since they're not overly intrusive, they're clearly labeled, and they're not targeted to me based on my personal information. Plus, DDG actually gives me the option to disable ads completely.
Personally, I don’t mind an ad or two. It’s not ads, per se, that have me using an ad blocker... it’s the “bad UI impact of tons of ads and pop-ups” that keep me in ad block mode. When a site wants me to turn off the ad blocker and it doesn’t look insane, I’m happy to comply. Same with DDG.
My worry is that if they ever achieved a dominant, Google-like position in the marketplace, that they would eventually lapse and go for greed. Even if the current DDG leadership is principled in this respect, companies go through turnover. Can't be evil > don't be evil.