Reagan was divorced. Bush had a drinking problem.
Okay...bear with me, I'm Canadian...
But what about Tom DeLay?
Both Reagan and Bush were twice governors of their states, California and Texas, before they ran for president. They had impressive resumes and the voters knew their experience at governing. Rudy has done a great job at being mayor of NY but really hasn't credentials impressive enough to get the support of a significant number of Republican party members, even without his messy, messy, marital history. I don't fancy tilting at windmills, which I equate with Rudy and his prospects of winning a presidential primary.