I'd say it REALLY depends on the implementation model. Non-intrusive adverts that are relevant to the content are something that I sometimes literally seek out

I'd say it REALLY depends on the implementation model. Non-intrusive adverts that are relevant to the content are something that I sometimes literally seek out - because they bring me information that I want, and may lead me closer to buying a thing I want. I've even been frustrated that an advert displays, and when I try to view it again to get more info, it's already gone. Sometimes, I buy trade magazines just for the adverts, or to scan the sponsors/advertisers guide at the back. At the other extreme are popup/pop-over/slide-over adverts especially on mobile that we cannot get rid of. Those are not an exchange of a portion of my attention to support what I'm reading, they are a wholesale hijacking of my attention and holding hostage the thing I want to read/view. It is literally like walking into the store and having my pocket picked. One model is completely legit, and the other is pretty much spam and legal constraints could be justified.