The first thing I look at is if candidate can sell in the Midwest since that's where most swing states are at.
Obama does scare me down the road. He's well spoken, articulate, and unless a complete disaster happens, will win statewide. He's also from the Midwest. Since he's NOT from Detroit, he'd probably be a threat in my own state since he won't be able to antagonize the Detroit suburbs in the racial politics that goes on between Detroiters and Detroit's burb - while at the same time getting votes there and in Southfield/Flint.
Bill Richardson scares me the most. Governor(outsider). Insider ties(Klinton). Experience(albeit not necessarily good experience). First Hispanic on a ticket. Westerner. At least somewhat pro-2a(Signed Conceal Carry). I think he can 'good ole boy' his way to a lot of votes up here.
Bill Richardson is troubling alright. I didn't even know he was Hispanic.