One of the more common technical SEO questions I see is why isn't Google showing rich snippets for my site when I have implemented them correctly. So we know that Google often won't show rich snippets if the site doesn't meet a certain (undocumented) threshold for quality.
But did you know that if you do a site command on a site that has implemented rich snippets, Google should show the rich snippets regardless of that quality metrics?
John Mueller said in a Google webmaster hangout at the 20:04 mark into the video:
Usually, if you do a site query for a site, we will show the Rich Snippets if it's implemented technically correct. So that's a good way to kind of double-check that we can pick up the mark up properly and we're not showing it in normal search results then that's really a sign that we are essentially not sure about the quality of the website.
So this is another good way to determine if you implemented rich snippets correctly. You don't just have to use the Google Structured Data Testing tool, you might be able to try the site command. Now if the rich snippets don't show for your site when you rank for normal queries, and it does show for the site command, then you may have a quality issue.
Forum discussion at Google+.