I see them quite frequently. And now using -pinterest doesn't work anymore, because they caught on and that string doesn't exist in their results.
Edit: "they" being Pinterest, not DDG.
You can also exclude by domain:
-site:pinterest.com
Pinterest has had many tlds for years to beat this trick.
as a ddg user I wish it had an option to remove stock images; some queries seem to return nothing but same-looking watermarked images for sale. but no issues with pinterest which I occasionally use directly