Earlier quoted context omitted.
So back when Blekko was a consumer search engine we could 100% figure out who owned content on sites we crawled often. And even when we didn't we could often guess correctly more often than not based on the domain registration dates. (not to mention registry owners). That is because few people who rip off content rip off just one web site, they will rip off dozens of web sites and they will all share the same AdSense…
Do you know if any search engine is actively filtering for this?
My guess, having been at both Google and Blekko, is that "whitelisted" search will be the next wave in the industry. For those old enough to remember Yahoo!'s original "directory" model, once Yahoo!'s contract with Microsoft is up one could hope they rebuild their search team and technology into something with a strong editorial bias for "quality" content.