[c22]

You could argue that web users with adblockers are rejecting these agreements by refusing to HTTP GET the linked ad content and that the sites are accepting the modified terms if they subsequently serve the requested non-ad content.

[darawk]

Yep, that'd be a reasonable case to make. Although the site could simply augment its terms with "Serving the content any way does not represent a change in terms; proceeding to consume our content remains in violation" to clarify.

[trothamel]

While we're into making one-sided arrangements, one could add to the HTTP headers: "Serving this request in any way consents to having the content returned displayed in a matter that is determined by the user-agent and the user. This supersedes any other terms of service that purport to governing the processing of this requerst."

This, at least, has the precedent of accurately describing how websites have been presented since the days of NCSA Mosaic.

At the end of the day, I'm not sure that unread terms presented from either side should have anything to do with it.