I was aware of it, actually. Several times when I'm looking for the answer to a programming question I Google it first, and tend to end up on a scraper's website. When I click "read answers" or whatever flavor of link they append, I'm usually directed to Stack Overflow or one of the SE sites.
On the one hand, it's frustrating to see someone else re-publish your work without your knowledge. But that's what the licensing of the site allows, to it's kind of the cost of doing business in a public forum.
On the other hand, many content scrapers link back to the site they scraped from. Which means they're becoming just that many more entry points to the site (i.e. someone Googles, gets scraper site, and follows it back here).
So when I weigh the pros and cons, I'm irritated but accepting ... in the end, I'm essentially cool with it and generally ignore it.