I can't think of a good example without giving myself away but my jw would often say it is all about 'motive' and being 'sincere'. They/he might have lied but their motive was good, they might have been false prophets err, said a wrong date but their motive was good and so on. They were sincere, the gb told them.... I have told him time and again that he must make sure of all things, it won't matter a hill of beans if in the end you say, "well, someone told me to believe and do this". You are responsible for yourself. (if you believe in an afterlife that is, if not, carry on, it doesn't matter then what you believe or do)
Diogenesister has it exactly right!