Bubbles - hangover affect !

There is a lot we could discuss about this but just a brief outlook. Prior to 1990 the frequency of these bubbles was pretty low when compared to their occurence now. We had tech bubble of the 90s immediately followed by the the gigantic housing bubble that led to the 2008 Financial crisis and it appears that there is a commodity bubble now.  A buubble is similar to a party that starts late in the evening, many people gets drunk past mid night. The next morning hangover will be nasty just like the recession which usually follows a bubble. The more we drink the nastier  the hangover. The housing bubble hangover is extremely nasty because of the free flowing cheap liqour in the form of very easy credit.  But how do we know there is bubble forming is some asset class, is it visible in some form or will there be any indication of that. Of course there will be some indications if we pay attention and are aware, there will be lot of TV ads, people chatting about that in weekend gatherings, party's etc and the ultimate signal is that when your barber talks about it. When we see this behavior and if we're already in the party it's time to leave.