Usually a partner can become unwieldy in how they place their foot on the floor, thereby generating this state of instability. Both roles can and do genrate this stuff on a frequent basis.
When one knee is slightly bent and turned inwards towards the other knee, the opposite hip is raised. This position is generally a Follower thing. It has the tendency to break the line of the couple and the verticle line of the Follower. Is it desirable ? Meaning do you want
Follower Bashing. Put simply, this is where a Lead blames the Follower for missing something musically, or kinesthetically, or not reading the Lead’s mind. This is really Lead arrogance that they’re being superior as dancers. And yes this happens quite frequently, more than you would think or like it to