Agreed that there are many sites that seem to have no other purpose than to get ads displayed.
Unfortunately, it's also getting harder and harder to tell them apart from the sites that have legitimate content supported by ads because the quality of the latter is nosediving.
The reason you can't tell them apart is there's no meaningful distinction. Whether content is sufficiently "legitimate" to be worth the ads depends entirely on the particular user.
I don't entirely agree. Yes, there's subjectivity, but there's more to it, IMO.
There are sites (eg along the lines of legacy print or established in the "early" internet days) that still try to generate news content for reading, but are seeking more revenue.
And then there are sites that are just modern click/impression factories that never tried to actually produce real content.
If that were really the case, then nobody would be employed to try and understand SEO, ranking algorithms, virality, etc.
Edit: what I mean by that is: I think your comment implies there's some sort of meritocracy to content people see online that isn't easily gamed. My various feeds, search results, etc, convince me otherwise.
Unfortunately, it's also getting harder and harder to tell them apart from the sites that have legitimate content supported by ads because the quality of the latter is nosediving.