a Rumour is a social cancer.

A rumor is a social cancer: it is difficult to contain and it rots the brains of the masses. However, the real danger is that so many people find rumors enjoyable. That part causes the infection. 

And in such cases when a rumor is only partially made of truth, it is difficult to pinpoint exactly where the information may have gone wrong. It is passed on and on until some brave soul questions its validity; that brave soul refuses to bite the apple and let the apple eat him. 

Forced to start from scratch for the sake of purity and truth, that brave soul, figuratively speaking, fully amputates the information in order to protect his personal judgment. In other words, his ignorance is to be valued more than the lie believed to be true.