So, do superbowl ads not count as ads because a non-negligible portion of the viewership wants to see them? Or are you saying that there needs to be a non-negligible fraction of the viewers who don’t want to see it for it to be an ad?
(Though, that doesn’t imply that the best available definition won’t have any edge cases like this.)
I think it works better to define whether or not something is advertising based on, rather than whether the viewer wants to see it, instead by whether those putting the media where it is intend for viewing it to be (as far as they can make it) a requirement for something else.
Though, I’m not sure that even that should be considered a requirement. It seems to me like the things businesses paid money to get put on the million dollar website, should count as “ads”. I don’t see why we should define “ads” to refer exclusively to objectionable ads.
A good (but not perfect) guideline is that voluntary transactions are beneficial to both parties because otherwise they wouldn't participate, and transactions where one party doesn't actively agree to it are often bad because the other party has no incentive to make it otherwise.
That's why I focused on whether the viewer actually wants it. If I seek it out, then it's useful or at least entertaining. If I don't, then it's probably a net negative for me.
And, while definitions may not be super important (as you say), and while it is often fine to redefine a word within some context, I do think the definition I gave is probably closer to how people usually use the word “advertisement”.
My inclination is to stick on an adjective though, and refer to, say, “unwanted ads”, rather than say that the ads in a classified section “aren’t ads”.
There are probably a decent number of football fans who would use a "skip ads" button if they had one for the Super Bowl, so they're still some way toward the "ads" end of the spectrum. But they're certainly less objectionable than most TV ads.