A very good instructor gave me this tip years ago - If roll control appears to be reversed, let go of the control yoke and just use rudder for secondary effects and then (if the design allows) hold the part of the control that emerges from the dashboard or floor for pitch attitude. Have tried this in light aircraft and it works well.
I mentioned this in the Embraer thread: if your roll control is reversed, lean over and grab the FO's inboard control column horn with your right hand and your inboard horn with your left and away you go. Wouldn't work in this case though if the spoilers were reversed. And good luck doing it in an Airbus... come to think of it, does a Glex have a control column??