It happened to me. Nowdays I am a really evil person by JW standards (and probably by Muslim, Buddhist, and secular humanist standards as well), but back in my teens I was actually a pretty good guy. The only sin I can recall committing was masturbation; other than that, I was squeaky clean.
Nevertheless, I found out later on that some pretty nasty rumors had been circulating about me which I was unaware of at the time. I have since traced them back to a close family member who was evidently attempting to slander me so she could create a rift between me and my friends (none of whom she liked). I'm ashamed to say that she lied to me as well and I believed her without ever investigating whether or not she was being truthful.
To be fair, I don't think this is unique to JWs at all. I've found that gossip and backbiting are endemic in human society no matter if it's a church, workplace, or school. People are bastards.