I don't know because after of make the calibration (only TOA) the false color composition (543 in Landsat 7) yet is different between 2 scenes. A scene looks opaque and another is clear (both are of the same place and the time is similar). The difference is that in one scene, the bands 4 and 5 are High gain and in the another scene are Low gain.
Is normal the visual problem? I assumed that the TOA correction should remove the angles's effects. How could make these scenes are seen with the same lighting?