Ben, sorry. I changed that back before I saw the reference to that conversation.
Is Spanish perhaps your first language? In English, "loose" can be short for "of loose morality", and synonyms might be "easy" or "slutty".
Does calling the woman a slutty bitch makes sense in context? She's half naked with Barr's son, so sure. And we can't ignore that no matter how bad a translator Google Translate might be, it isn't going to translate "Feathery" into "Malkompaktan". The author definitely meant "loose", even if that might not be the best word for what he was trying to say.