I'll put my vote to "bad" thing to be drinking. Some people may argue that cow's milk is the cornerstone of nutrition for children, bodybuilders, etc., but common sense tells us otherwise.
First off, a cow produces milk for one reason: human consumption? No, her offspring. That's it. We are the only species on earth that continues to consume milk after we've been weaned from it at around 2 years of age. We do not manufacture the necessary enzymes needed to break cow's milk down properly and utilize it. Lactase, which is one of them, is missing in about 75% of the population. So, yes, most of us are "lactose intolerant".
As for the calcium, find another source. In fact, many times, milk actually causes the body to LOSE calcium. Why? Milk is acidic to the body. (*Acid/Alkaline balance is very important to one's health, and the body works hard at maintaining that balance, often with the help from calcium.) So when you consume milk, the body will not only use the calcium from the milk you just drank to keep the body alkaline, it will also take some of the calcium from your bones. (Fact: North America, highest consumers of milk, also highest osteoporosis cases. Countries that drink the least amount of milk, lowest cases of osteoporosis.)
Milk causes more allergies than any other food.
Milk is mucous forming. If you drink plenty of milk, you probably have plently of flem. It creates great loogies to impress your friends, but that mucous slowly accumulates throughout your body.
Pasteurization destroys the natural enzymes present in fresh milk.
There are a couple of exceptions. Plain yogurt, ok. Cottage cheese, ok. If you don't mind the fat content, and must drink milk, try goat milk. Cow's milk can take up to 3 hours to digest, whereas goat's milk 30 minutes. Also, goats are hormone free, if that is a concern.
Sorry for the novel. Most "modern" nutritionists, chiropractors, naturopaths, etc. will agree with the above statements. Most medical doctors, however, will not. They are not versed in modern nutrition, let alone any nutrition. But that's a topic for another day
...Pete