In addition to violating the prohibition against listening to loshon hora, every listener of loshon hora is, in effect, making it possible for the speaker to relate his forbidden words, and therefore is an accomplice in his sin.
In the case of a lone listener, the prohibition before a blind person do not place a stumbling block (Vayikra 19:14) would surely apply, for included in this verse is a prohibition against causing another Jew to sin. We will see that in certain instances listening to Loshon Hora is forbidden not because of the primary prohibition but because of the prohibition against causing another Jew to sin.
