In asking if "Black Magick" is evil one must further ask if their "intent" is evil. A history tidbit should change perspective, in late 1700's to early 1800's categories were given to label books and knowledge (the academic approach verus the religious approach) within the occult area. In those times Black topics included various ways to kill, poison, and manifest one's will in an unscrupulus manner. Gray covered a balance between Black and White; and White included ways of healing, giving life, and overall a more ethical way to practice. Its also a popular way to clarify spells to make the look up a little easier.
As time progressed then original meanings have changed into more confusing meanings such as Black being selfish, and in aims to destroy one's self. Gray is typically still balanced, however one could produce malice out of ignorance, and White remains more of the "love & light" ilk. Though generally lacking interpretations, it comes down to intent. What do you intend to manifest with your will? If you figuratively sell your soul to Satan to achieve mass wealth you are working Black Magick. If you go out of your way and perform a ritual so that your neighbor recovers from an illness, you are performing White Magick. Then there is the lovely Gray in which 90% actually live in and practice on a regular basis, whether we acknowledge it or not.
To further make that last statement understandable, in the mid 1900's holistic medicine was becoming more and more popular as people were realizing that the era of great medical advancement still had its limits. Canacer patients were as prevelent then as they are now. And many sought additional treatment from Holistic healers (or basically pagan practitioners), now to set the scene. A cancer patient comes to you to ask for healing, and you hypothetically heal them of their cancer. What type of magick did you just perform? Due to interpretation you just did all three; black, gray, and white. I know the usual argument is white however that only covers one facet. In order to cure the human host of cancer, you must kill a living organism (the cancer cells)..you just practiced Black Magick. However you did it to heal and save the human's life..you just practiced White Magick. As with most illnesses one of the living organisms must die in order for the other to live. Either the cancer cells die so that the human may live, or the human must die to become food or basically a giant petri dish of death.
In the end the more appropriate label would be Gray Magick. This is something a lot of practitioners miss, especially new to the craft. We do not live in a world where life is fair, or perfect. Nothing is cut and dry, so why would Magick be? Magick is more than a religion or spiritual practice, its apart of daily life. It changes just as you do and the world around you. Everyday you make decisions and perform actions, some out of selfishness, some out of generousity, and some in-between.
New quick scenario: Guy breaks into your house and is holding a member of your family hostage through violent means. Say you in one form or another hurt the assailant to protect your family. Did you just perform a Black, White, or Gray action?
Bottom line we live in a Gray world, and make Gray decisions daily. Something will always lose so something else can gain & vice versa. Best to just ditch the color labels in your practice, try to do right by your friends and family. And if you are doing something that doesn't sit right with you, stop doing it and find another route.
Welcome to the colorful reality.