Its the ones that cover the whole screen, have someone who talks over the speakers, or force me to find a tiny hide button that I want blocked. So far, i have not found that Google, Microsoft, or Amazon do this. (SO FAR.....) Also, i run a site that uses Google Doubleclick for Publishing that houses some ads as part of the site's content. They are not obtrusive and you would mistake it for the site's content. Adblock will block them though, even though they are just in-house ads for my own content on the same site.