I remember trying OpenDNS in 2008 and seeing that, and yes, I found it such a shady tactic that, taking into account Google DNS exists, I will probably never give a second chance to OpenDNS.
A shame OpenDNS used to redirect me to some spam webpage every time I tried to resolve a domain that didn't exist--they earned a spot on my black list forever. :(
Facebook assumes that advertisers will be offended because advertisers assume that a certain % of consumers will be offended and they'd rather not lose that %, as small as it might be.
The only ones who are offended are the advertisers. As a far right winger, I can't see anything wrong with making sure our women are in good health. :)