I've seen Al Gore within twenty feet at some political photo op when I lived in Tennessee, previous to the Clinton-Gore presidential bid. There is no way I would believe him to have a PDD of any sort. He is not just a liar, he's a really good liar. Some of his lies are not good, however. He did not invent the internet and his "love story" was never made into a movie.
I don't think he came up with the inventing Internet rumor. His political adversaries did; he expressed himself rather clumsily about how he got funding for it in the eighties.
... and he knows how to turn that kind of BS into a positive, better than many politicians. Whether you start a lie or not, plays a small part in how you actually use it and benefit from it, most of the time. He might be dangerous. I first became aware of him when I lived in Tennessee and he was moving up in that state's politics. I liked him then! He was also a big fish in a small pond, while serving Tennessee, but the caseload that accompanies national politics has undeniably taken a toll on his credibility, as he tries to swim in the "big water".
I would choose Gore over Hillary, but I'm afraid that may be the exact form of the Democratic ticket, in the next presedential election. We may get both.
MODDED TO ADD:
Yes, I've seen the statement he made, denying that he is preparing to seek the nomination.