Nick,
Sadly this pattern is repeated for more than just gaming. A lot of people have formed opinions on different topics based on what they have heard and never check out the facts.
People have been persecuted because their beliefs have been misunderstood. So, I am not surprised at snap judgements on role playing.
Sometimes, I think half the evils of this world would be gone if people would just check facts before forming opinions. Too often people form an opinion and try to force the facts to fit that opinion.