WF
You seem to be there now. One of the things that I think may have made you uncertain was your repeated use of the word ineffective. To me that word means that whatever one is talking about has 'no effect'. In actual fact what is really needed/meant in the circumstances of this topic is 'reduced effectiveness'.
Keith has made it quite clear why reduced effectiveness happens and what the various fixes are.
A final point is you mentioned 'control reversal'. This just does not happen through purely aerodynamic reasons. It happens if the torque needed to move the control surface (usually ailerons) is so great that it causes the wing to twist. So a down going aileron can twist the wing trailing edge up to such an extent that the overall net aerodynamic rolling moment is opposite to what the control surface (pilot) was asking for.