There are two main reasons that Republicans get the evil image; Religion and Economics.
First, politics should never equal religion. Religion should have no bearing on any political, federal, or governmental issues, But, unfortunately, in the US we still use the Imperial units of measurment and have a very Christian society. Like Fajita_Jim said, all a candidate has to do is hate the rest world and love Jesus and he will find a great deal of misguided American support.
Being a bible thumper doesn't make anyone a good candidate. However, a good candidate could also be a bible thumper, but not likely. We are supposed be a secular nation, the founding fathers intended it to be so. We have Freedom of Religion, that includes no religion. I'm an atheist and a liberal/libertarian. I know those two aren't exactly compatible, but if I can't be a libertarian, I'll be a liberal.
Second, trickle down economics don't work anymore. Tax cuts for big business' end up lining the pockets of the Executives. Not all companies are guilty of that, but I am forever biased against lobbying. If lobbying didn't exist, the world would be better for it. At least lobbying in the sense that big companies can buy politicians.
We are supposed to be a Capitalist nation, but corporations get more charity than the poor.
But the Republicans are not solely to blame. We've had some Democratic blunders in my lifetime. We are not the world police. We are not the world's charity box.
I'll be voting for Ron Paul, if he gets the nomination. I believe he's a stand up guy and the only person qualified to be a presidential nominee. Knowledge of the constitution and the courage and discipline to live by it are rare things in our government.
We haven't had a strong third party in a long time. I'd love to see a third party, or fourth party, emerge in my lifetime. The US has a constant tug-of-war cycle between the left and right. It'd be nice to see a forward pass.