I recall a rainy day at a ren-faire - various musicians, actors, and what few patrons there were (very few) were gathering in sheltered spots and music was going on -

I sang a song; and shortly thereafter was ripped into by an actress saying it was "her signature song" and how dare I sing it, etc, etc, etc. Turns out she did not know who had written it (I did) nor did she have his permission to sing it (I did). She had learned it from a bootleg tape - I had learned it from his performances.

*le sigh*