This picture is upsetting some people:
The ad, beside a story about the 12-year-old boy who shot and wounded two classmates Tuesday, offers website visitors sales and discounts on guns, ammunition and training classes.
A similar incident occurred earlier in January when Connecticut newspaper, The Stamford Advocate, ran a very large gun advertisement next to a story about the first day back to school for Sandy Hook Elementary students. The newspaper later apologized for the “insensitive” error.
Source: http://www.huffingtonpost.com/2014/01/16/albuquerque-journal-gun-ad-school-shooting_n_4611107.html
Yet there’s a technical explanation:
Context-sensitive ad servers base the ads they serve up on the text on a page. I have a page with an HTML generator on it that has power generator ads displaying, and gluten-free recipe pages that display ads for bulk gluten.
A site can block an ad they don’t want to display on their site, but they probably don’t want this ad to be completely blocked, because (at least if it was displaying next to appropriate content) some of their readers will click to buy the product (and earn the paper money). I had to completely block google ads on one of my site because inappropriate ads kept coming up that would have resulted in my site being blocked by a different sponsor.