Carnivorous plants have a reputation of being something of the rogues of the plant world. You might not really think much about your meat-eating-plant pet succumbing to silly illnesses and infections. However, just like any other plant, carnivores do have some natural disease weaknesses that can create serious problems for them and even kill them if left undiagnosed and untreated.
This infection affects pitcher plants in particular, but most carnivorous plants can contract it. The infection tends to enter through the roots and move upward, creating discoloration in your plant as it goes. Discoloration can be harder to spot in carnivorous plants because they are often unusual colors. Red may fade to pink or gray rather than turning brown, for example. Often the plants lose their shapes and appear to "melt" during this infection. Infected plants do not usually recover from this disease, but you can salvage your healthy plants by removing them and repotting them in clean soil. Wash them first to remove potential contaminants. You may also try a systemic fungicide to try and save infected plants.
Slime mold and sooty mold are both problems for carnivorous plants because they live in humid, boggy environments. These molds are dark--usually black--and cover the leaves and stems of the plants. You can simply scrape the mold off in most cases to keep it under control. Sooty mold, which has a more powdery appearance than slime mold, may indicate a need for an insecticide, since it often heralds the presence of scale insects. If the mold becomes a serious problem, scrape it all off your carnivorous plant and repot the plant in new soil.
Spot diseases cause small, spotted discolorations on the carnivorous plants. Left untreated, the spots will cover the entire plant and eventually cause it to rot away. Black spot typically impacts flytrap plants, while rust spot typically is a problem for nepenthes. The spots' color is denoted by the name. Just because your spots are not the typical color for your plant's typical infection, however, does not mean that you do not have a problem. You need to treat the plant with a fungicide immediately, remove the affected leaves if possible without destroying the plant, and replace the soil with new potting medium.