One of my main goals with SearchMash has been to save search time by skipping pages that don't actually have the terms I want, despite what they tell Google. Typically, these are subscription sites that require registration and login to see the information Google's indexed, and that's normally too big a barrier for me.
To avoid those pages, SearchMash now checks the web pages it gets for the search terms, and tells you if it doesn't find some of the terms.
I also upgraded the status display of results over the weekend, so you'll see a clearer indication of any problems getting the page. I now draw a line through pages that couldn't be fetched, and color any links that had errors as red.