@Faket Assuming we are talking about skim milk here, it is low in fat, low in sugars, and is a decent source of vitamins. Its hard to frame it as unhealthy, in fact I'd say its probably one of the healthier drink choices. Sodas are just a pile of sugar, even vegetable and fruit juices can be way too high in sugar to be healthy.

Fat content, which is quite low in skim milk, is the only reason I could think of that someone might think it unhealthy, so really cant imagine why you'd think that.