Are you only crawling or also scraping the website? If the sites in question only add an exception for googlebot and not other crawlers (e.g. Yahoo, bing, etc.) I would say that it is against the site owner's consent. However if the site owner adds this exception also for other crawlers, you could argue that the site owner's intent of only allowing certain crawlers has not been made explicit. In that case you'd have…
Genuinely curious: on what basis? Can you trademark (or similar) a user-agent?