Cheney for his entire life has basically not given a single fuck about his reputation. He's completely tone deaf to his image, which I happen to think is rather unfair, and he never would have been able to run a Presidential campaign or appeal to people. His finest moment as a politician was his smack down of Edwards in the 2004 VP debate. That was tearing someone down, not building himself up.
I also don't think he would get past the Primary electorate of 2000 for the GOP. Post Lewinsky, there was definitely a moralist undercurrent in the party base, and Cheney's support for gay marriage or civil unions (I think he has a gay daughter) would not go over well. McCain would have the maverick label and would take Cheney's support from the foreign policy establishment (remember, the realists and Neoconservatives all were behind McCain in the 2000 Primary, while the isolationists were behind Bush or were backing Pat Buchanan), and the fiscal conservatives had Steve Forbes, while the social conservatives had Alan Keyes. Cheney had no base from which to run from.
Also, was there ever any indication, ever, that Cheney wanted to be President?