Why are my feet looking so dusky?

Smoker?: Given that you have copd, it is pretty safe to assume you are a smoker (or at least you have a history of heavy smoking). Nicotine causes the small blood vessels (capillaries and the like) to constrict. This is most obvious at the tips of the toes and fingers, which can begin to appear "dusky". This can lead to serious problems, such as dry gangrene. Must stop smoking, and see a podiatrist.

Many possibilities: There are many things that may cause a discoloration of the skin. Several types of inflammatory conditions of the skin, allergic reactions, and sometimes bacterial, viral or fungal infections and cancer can cause a discoloration of the skin. Insect bites can also be the cause of a rash or a discoloration of the skin. Have it evaluated by a professional and get the appropriate treatment.