I just happened to notice Google ranking Google Trends for [sex]. Page two result - not bad at all for the highly competitive search term.
Google do use robots.txt to block the url snippet
/trends?from their results. However, what we have here is a (at least one expert) site linking to Google Trends using [sex] in the anchor. You can see this in the title Google's given to the result - that's the anchor text. The lack of snippet means Google's not ever been to the page. In a way Google are falling foul of their own system (provided Google Trend results in Google's SERPs are seen to be a no-no in the same way as YouTube search results were).
Okay. So why was I searching for sex on Google? A client's Webmaster Console over at Google suggested that they too had a fairly good rank for [sex].
In the UK this report is often wrong. I can't find the client's site anywhere near the reported position. Perhaps there are lots of people with personalised results strongly in favour of our client and who research for these terms.