For one, many of the translations are just terribly wooden.
But Russian is also very hard to translate to English, for several reasons; it's a heavily idiom-based language, full of common phrases (that every Russian knows) that an author can turn into puns or allusions. If the translator chooses to rewrite using the equivalent English idiom, the original meaning may be lost; whereas if it's translated literally, the reader won't know that it's a common saying that the author has subverted. The same thing goes with words that have multiple meanings, where the ambiguity itself resonates within the phrasing, or where the word has historical subtext or whatever.
But translators also often get stuff wrong. Plenty of people have pointed out very clear errors in the Pevear-Volokhonsky translations that are based on misunderstandings of the original text. Bulgakov also frequently writes on several levels (there's a lot of subtext and humour), and it's often hard to replicate the intended meaning, so translators end up with something that isn't quite right. Here [1] is some discussion with concrete examples.
But Russian is also very hard to translate to English, for several reasons; it's a heavily idiom-based language, full of common phrases (that every Russian knows) that an author can turn into puns or allusions. If the translator chooses to rewrite using the equivalent English idiom, the original meaning may be lost; whereas if it's translated literally, the reader won't know that it's a common saying that the author has subverted. The same thing goes with words that have multiple meanings, where the ambiguity itself resonates within the phrasing, or where the word has historical subtext or whatever.
But translators also often get stuff wrong. Plenty of people have pointed out very clear errors in the Pevear-Volokhonsky translations that are based on misunderstandings of the original text. Bulgakov also frequently writes on several levels (there's a lot of subtext and humour), and it's often hard to replicate the intended meaning, so translators end up with something that isn't quite right. Here [1] is some discussion with concrete examples.
[1] http://www.thevalve.org/go/valve/article/translation_wars_on...