Quinlad, What's 'incon'?
I'm not sure whether you're talking to me, or to Octavius, since he's the one who denies that ghosts can be seen, and you're asking about people who see 'visions' (for want of a better word). However, I'll give you my answer.
These people's testimonies don't necessarily carry less weight, which is the point I was making about Moses. However, since we have nothing to tell us what Mary or Jesus looked like, the people who claim to see them have no way of recognising them, and therefore no one can ever be sure what or who they are seeing.
In the case of Moses, however, he did, apparently, hold a conversation with Jesus (along with Elijah), and since that meeting is recorded in the bible, and since Moses died long before the event, the disciples could not possibly have known him, so we can only assume that he told Jesus who he was.