Can't be? That's taking things to an extreme on your part, but statistically, I'd say conservatives tend to not get as caught up in the trappings and power of the office as Democrats seem to.
Maybe it comes from the notions of self-reliance and more of an adherence to the principles of their faith? Or maybe it's the double standard and level of attention that the press focuses on conservatives vs. progressive liberals?
Either way, the risks of crossing the line tend to be higher than if you're a Democrat. Republicans abuse power, and get brought up on charges. Democrats can do lines of coke with a bunch of prostitutes, have spectacular DUI events splashed onto YouTube, send selfies of their privates, and that just seems to give them street cred. It's absurd that someone convicted of drug offenses or who killed someone else while driving drunk can get re-elected repeatedly. You'd never see that with a conservative.