Nothing influences the taste of coffee more than roasting.
In appearance roasted beans can range from light brown with a dry surface through dark brown with an increasingly oily surface to black with an almost greasy look. Until recently preferences in roast style, like so many other cultural choices, were traditional. Of course one of the frustrations of home roasting is that once you get a batch of beans that tastes exactly the way you want them to you may have trouble precisely duplicating the procedure that produced them. But if you are at all systematic you can come very close to consistency, and home roasting is for romantics and adventurers anyhow. Those concerned purely with uniformity probably should stick to buying coffee from the store.