1. Do you trust this unjustifiable idea?
Yes, although I would look into it more (ie do a second interview with the seemingly perfect but shady person). I've been right about this sort of thing too many times to ignore it.
2. Which one would you hire?
If I had to hire one of them and not keep the position open, I would hire the average one.
3. How certain are you of your decision?
Pretty certain. If someone makes me uncomfortable, it's almost always for a good reason.