A "blue
cloud" is a dangerous area effect resulting from rapid, sustained utterances of profanity. Those in the area of effect experience either anxiety or elation depending on their idiosyncracies. Often encountered at
truck stops or in the homes of desperate housewives. See also "turn the
air blue".
If this therapist dislikes profanity, it won't
work for
us, because there'll be a blue
cloud of profanity in the room.