I don't suppose you'll tell us how you know whether a site's content is original or not. What if you have a blog with lots of quotes from other sites; will tha

I don't suppose you'll tell us how you know whether a site's content is original or not. What if you have a blog with lots of quotes from other sites; will that hurt your rankings because Google sees "unoriginal" content? Is there some ratio of original to unoriginal content that must be met to keep from being flagged as a scraper?