I've mentioned Jim Chanos before in this blog, and he's out again with some telling examples of late stage 'exuberance'
While Mr. Chanos is almost never perfectly timed with the market's current mood, he is rarely wrong longer term.
http://www.bloomberg.com/news/videos/2016-06-15/chanos-easier-to-find-short-ideas-as-bull-market-goes-on