They forgot about that "audience research" quickly then. This will not make her more likeable.
What was wrong with Michelle/Nick etc finding out that Johnny was Carla's dad, keeping it from her for fear it would send her back on the path of destruction; Carla leaving because she found out and felt betrayed by everyone?
Were Rob and Carla originally full or half-siblings? I can't remember. Has their mum always been said to have had a reputation or did they suddenly invent it for the purposes of this storyline?
So Carla was married to her first cousin once removed? Second cousin? Some form of cousin anyway. Time for another Jeremy Kyle Coronation Street special?