Well, ribit ... I am compelled to say some things in defense of what you call an "all or nothing" attitude, my friend. First of all, screw the left-wing, right-wing, Liberal, Conservative, Demodumbfuck, and Republican labels ... that's all meaningless posturing of one sort or another. Ultimately, the bright dividing line is whether you believe in the primacy of government rule over individual rights (tyranny) or the primacy of individual rights over government rule (freedom). Statists fervently want to grow government rule, irrespective of what harm that might do to the individual rights and freedom of American citizens, because they believe it redounds to their personal benefit. In other words, they are narcissistically selfish in their almost complete disregard for the well-being of their fellow citizens. The reason why the statists can afford to be somewhat forgiving in how ideologically pure their candidates are is because, while a statist-light might not move their agenda forward as fast as a true believer, he'll still apply some amount of slime to the slope and keep our country moving downward into the abyss - just at a slower pace. If Republican candidates are not pure in the sense that they not only want to stop the statists' agenda of decline but reverse it, then they are nothing much more than a statist-light ... and we're still sliding into the abyss. That is why Conservatives have to be more particular and demanding about their candidates, in my humble opinion.
B.

The essential American soul is hard, isolate, stoic, and a killer. It has never yet melted. ~ D.H. Lawrence