According to the stackexchange scraper policy you shouldn't report sites that:
They follow all the attribution requirements, and don't outrank us on Google
I've been thinking several ways to use SE scrapers and show the information in different ways, but this policy bothers me.
You can't detect easily a website who is outranking you in Google's SERP, because there are so many variables that each search takes into account that every user can see different results. There is no a single way to detect this, may be a webpage does better than another one for a group of keywords but that doesn't means it outranks the whole site.
Unless this is based on some external index like Alexa or similar rankings.
So, how does Stack Exchange identifies another website outranking them on Google?