Some molds are beneficial, especially those in foods. Molds are used to make certain kinds of cheeses such as Blue Cheese, Roquefort Cheese, Gorgonzola, and Stilton. The blue or green like spots and streaks you see and taste are created by the introduction of P. Roquefort or Penicillium Roqueforti spores. Some cheeses like Brie and Camembert have white surface molds. Some cheeses can have surface mold and internal mold. The molds used to manufacture these cheeses are safe to eat unless you happen to have a sensitivity to them such as people with allergies to Penicillin.
While most molds grow best at elevated temperatures, but they are opportunistic and can grow quite well at temperatures we humans find comfortable, and can also grow at refrigerator temperatures. Molds are quite hardy and can tolerate some salts and sugar. As such, molds will grow in refrigerated jams and jelly, on salty meats like ham or bacon, and on most nuts. The mold found on peanuts is what actually causes people to have peanut allergies.
If you have food allergies, it’s quite likely some of them are caused by your personal sensitivity to the molds present on that food. You can develop sensitivities overtime and some foods that didn’t bother you when you were younger may cause some nasty ailments for you now.
Most molds you find growing on cheese without mold added aren’t likely to harm you, but the best bet is on hard cheeses like cheddar the visible mold can be cut off and the cheese can still be eaten. Cut at least 1 inch deep and around the mold spot in all directions being careful not to get the mold on your fingers or the knife and end up spreading the spores or injecting them further into the cheese. Mold growing on soft cheeses may have long deep invisible roots and if your worried about the mold, those cheeses should be thrown out. Never eat any meats with mold on them, throw them out!