1. Never buy a stock with a price:sales ratio greater than 5.0. FB price:sales Price/Sales (ttm): 18.01 which is a nightmare waiting to happen number. Called "castles in the air" or balloons ready to pop.
2. Never buy a stock with a p/e ratio greater than 30. FB forward p/e is 26.58 which is "o.k." but not enticing.
3. Never buy a stock, regardless of p/e ratio if the PEG ratio is greater than 1.0. FB PEG ratio is 1.06, about 6% too high.
4. Never buy a stock where debt exceeds cash. FB passes this one with flying colors with over $6 cash per share.