Liguy, it is very well known in electrolytics. If an electrolytic is used as a coupling cap, the cap must be biased with a DC voltage that is larger than the AC signal it is being used to couple. Electrolytics *really* don't like being reverse-biased, which would happen on part of the waveform if the first part of this statement is not realized.
Now in crossovers, 'non-polar' electrolytics have been used for years, but that technique produces distortion because of this bias issue. If they are to be used successfully in a crossover, the caps have to be biased with a battery. When this is done they easily operate with the performance of film caps.
