Quote from Ghost of Cutten:
P/Es can be almost worthless because they are historical. It is future earnings that matter, not past earnings. Ditto for PEG and, to a lesser extent, dividends.
Relying on things like P/E or dividend yields is how a lot of non-value investors lose fortunes getting suckered into value traps, like Bill Miller with Fannie Mae (meanwhile I was shorting it down to low single digits despite being a value investor myself) or Mohnish Pabrai with that financial stock that went broke.
A value investment is something that i) has practically no chance of going broke ii) is so cheap that even in the worst case scenario, you will make money.
So for example, a company which owns $100 million of real estate, has $40 million of long term debt, and is selling for a market cap of $10 million, with a dividend yield of 30%, would be a value investment.
True value investments tend to only present themselves near bear market lows, or when individual companies or sectors are in serious short-term trouble, or when a stock/sector/market/country has been ignored for years.