I think every value investor dreads a value trap which is basically a company, which seems cheap by historical standards and the gap between the price and the supposed intrinsic value does not close.
I found the following very useful comment from bill miller (he is a very famous money manager in the US whose fund has beaten the index for a straight 15 years)
"You never know for certain, but the nature of value traps is, they tend to have certain characteristics. Typically, one is that the valuation of the business or the industry is lower than its historical norms. The company or business normally has a fairly long history, so the historical normal valuations provide a lot of comfort. Therefore, when you get down toward the lower end of these valuations, value people find them attractive. The trap comes in when there's a secular change, where the fundamental economics of the business are changing or the industry is changing, and the market is slowly incorporating that into the stock price. So that would be the case over the last several years with newspapers. They are a good example of where historical valuation metrics aren't working."
The complete article is here
In addition found the following interesting quote from warren buffett
“Margin of Safety is the untapped pricing power in a business.”