Whether or not:
He was born in Kenya or Hawaii...there is too much of his birth certificate that is refuted, for me to trust it...especially, since he's a liberal.
Whether he migrated back to the U.S., after being a citizen of Indonesia, the proper way, which also would have disqualified him.
Even if he was legal to hold the office, I believe he claimed to be a foreign student and got foreign aid and that's why he wouldn't show his school records (this wouldn't have legally disqualified him, but seeing he did something so underhanded, he would have been unelectable).
Being a closet homosexual/bisexual....we all know about him being a druggie, but if he had have admitted to having a homosexual experience, he also would have been unelectable.
My basic theory is that, he "possibly" may not have been eligible to hold office, but if any of his skeletons (more than that of which I named here...like being a communist, american-hater) had have come out, he would NEVER have held office.