Valuation bubbles seem obvious after they collapse or have a big correction (in fact, they often seem insane in retrospect), but is it possible to tell when you're inside one? If it is obvious to most investors that there is a bubble, presumably, that bubble would be likely to burst quickly. So, we shouldn't expect it to be particularly obvious from the inside of a bubble that one is currently happening. That being said, here are some signs that I think tend to be predictive of bubbles (t...