Needless to say, some are undeniably in poor taste. Many clichégenically, unapologetically, sexist. For instance, these from our very own (rabidly right-wing and very wealthy) hosting service, GoDaddy:
Why we are still hosting with these jerks, I sure dunno.
Others, largely philanthropic, fall into a different, mildly more interesting category of censorship. See for example this one or this one. These ads seem to pose an actual threat/provocation to the comfort of, you know, whatever Zizek is calling it these days.