Exactly how bad does bad cheese smell?

Dear Matthew Alice:

To determine if food items have outlived their edibility, expiration dates and pungent odors are probably the two most obvious ways to make a conclusion. Recently I was given a sizable chunk of Limburger cheese wrapped in foil, so I'm without the benefit of having the expiration date to go by. Which brings up my question. Does Limburger cheese start smelling good when it's bad?

-- Terry Markham, El Cajon

Bad, like inedible, or bad like deadly? Conservative cheeseheads tell me that any semi-soft product like Limburger is past its gourmet prime within two weeks of unwrapping it, when it will begin to smell "good" only if you love the scent of Limburger and ammonia. If a soft cheese begins to smell like it could strip wax off your floor, then it should only be used to strip wax off your floor. Ammonia a natural byproduct of the breakdown of amino acids by the three types of bacteria that create the characteristic smell and texture. Too much ammonia means your cheese has gone south. Unpasteurized milk can turn into life-threatening cheese; most harmful bacteria creep into the product somewhere between the cow and the ripening vat. But if no alien bacteria have invaded, Limburger is not the cheese of death.