Should hard cheese with mold be discarded?

Opinions differ a little, but the general message is to be cautious. According to the National Dairy Council, it’s okay to keep the cheese if the mold growth is confined to a small area. If that's the case, simply remove the visible mold as well as an additional 1/2 inch of cheese on all sides of the mold just to be safe. Although most molds on cheese are harmless, some may produce toxins that can spread into the cheese.
 
Here’s somewhat different advice of food scientist  Susan Brewer, Ph.D.:  “Cheeses with mold as part of the process of making them (Roquefort, Stilton, Gorgonzola, Blue, Brie, Camembert) can be trimmed as long as you can trim off at least 1 inch. (However, the moldy flavor may have penetrated the product.) These cheeses are manufactured using mold.  Generally, the mold on the surface is the same as what was used to make the cheese (which is safe).  Other hard cheeses with mold on them should be discarded.  They were not made with mold; they were made by bacterial fermentation. The mold on the surface could be any type.”
 
When removing mold, be careful not to cut through it, which could cross-contaminate other parts of the cheese. If mold growth is widespread, the cheese should be discarded.
 
Source(s):
National Dairy Council "Cheese"
Susan Brewer, Ph.D., University of Illinois, Department of Food Science and Human Nutrition