A revealing chart below mapping the recovery in employment from a crisis/recession till pre-recession levels. Its revealing in the sense that once they got back to pre recession levels, there is usually a good time to be had by bulls for at least 5-7 years before they next correct.
Hence while I believe the current global markets are a little frothy, we will have to learn to live with that kind of froth for some time still. Jeremy Grantham, whom I respect a lot as a value investor, said it best:
"We are not even that close to a bubble. With the S&P 500 at around 1860 (now 1949) recently, we are at about a 1.4- to 1.5-sigma event. Another way to say that is that we are between one and two standard deviations outside the normal distribution of stock-valuation levels. A two-sigma event would put the S&P 500 at 2350. So using the standard definition, it has to go up another 30% from here to get to a bubble. But you don't know when an ordinary market move is a bubble; you only know that in hindsight. "