NEW YORK ( TheStreet) -- Amazon ( AMZN) investors can be forgiven for believing profits are inconsequential. Year after year Amazon has successfully sold the idea that when they finally do push some of the top line down to the bottom line it's "going to be astronomical."Eighty-four is the number that should burn inside the head of anyone considering picking up this ticking time bomb. Amazon's price-to-earnings multiple is 84. Historically, stocks with a price-to-earnings ratio of over 20 don't perform above average. Currently the S&P 500-tracking SPY ( SPY) has a multiple of about 15.5.