About 1970, there was much speculation that Paul McCartney was dead. Offered as evidence were the album cover of Abbey Road, in which Paul walks barefoot, the others shod, and a song that played backwards might include the words "Paul is dead." There may have been other bits of evidence, but those are the only I remember. The speculation ended after some days when McCartney, who had been relaxing on one of his properties, returned to the public eye.
It did not occur to me then that this might have been somebody's publicity stunt, but I was a lot younger and hadn't heard the word "marketing".