I've read a few different things about this, not all of them consistent. I would love to get a native's opinion. Here's a couple of the good bits I found.
Here's one thing (source: http://blogs.transparent.com/italian/adjectives-and-their-position/):
When an adjective comes after the noun its position is more emphatic, and the information added by the adjective is fundamental to the understanding of the noun, e.g. le case vecchie del paese sono costruite in sasso (the old houses of the village are built of stone), implying that only the old houses are built of stones, and that there are also some new houses which are not built of stone.
When an adjectives is before the noun, its value is reduced and the information given is extra but not fundamental to the understanding of the noun. So by simply moving the position of the adjective in the following way: le vecchie case del paese sono costruite in sasso changes the meaning to: in the village all the houses are old and built of stone. The adjective vecchie (old), is not an essential piece of information, and could even be left out without changing the main point of the sentence, which is that all the houses in the village are built of stone.
Here's another (source: http://italian.stackexchange.com/questions/1248/what-is-the-rule-for-adjective-order)
Basically, when an adjective states an objective property of the related noun, it tends to keep its "regular" position, which is usually after the noun itself.
When there's some kind of subjective evaluation, usually the adjective is placed before the noun. (On the other hand, please keep in mind that this is not true for all the cases when the adjective preceedes the noun).
un povero uomo povero - un povero uomo = a poor (=pitiful) man - un uomo povero = a poor (=with no money) man
Good translation. In Italy no one would actually say "puro caffe nero" or "pure black coffee" in English. I wrote - and it was marked incorrect - "I take my coffee black," which is correct and in reporting it I added that caffe nero implies that it's pure and unadulterated. Again, it's an understandable problem of non-native English speakers trying to make the translations work in both directions, which isn't always natural.
"dark" in relation to coffee usually refers to the color of the coffee bean after it is roasted. Dark coffees are ones which are roasted a long time - espresso, French roast, Italian roast, and some others. Certain types of coffee beans in the US are typically "dark-roasted" - coffee beans from Sumatra, for instance.
Once the beans are ground and the coffee brewed, then the name or style of coffee (Sumatran, French Roast) carries with it the sense of taste the drinker will encounter, but "dark" is still just a reference to the quality of the roast, not the color of the brewed coffee.
Even a very lightly roasted coffee (often referred to as "blonde") can be termed "black" as long as it contains no milk or cream. "dark" isn't relevant to such coffees.
In a lot of South American Spanish which tends to be heavily influenced by Italian due to immigration and common Romance roots you can use "puro" (which also literally means 'pure' in Spanish) like you would use "only" in English... I would even say that saying in Spanish "Bebo puro cafe ❤❤❤❤❤" translates as "I drink only black coffee" or "ella come pura carne" would be "she eats only meat" (where as "bebo cafe puro ❤❤❤❤❤" translates better as "I drink pure black coffee". I saw someone asking about that below). So... I said that this sentence means "I drink only black coffee". Any native speakers of Italian that also speak Spanish that could confirm?