Rinos do exist, and they are often deserving of criticism. Snowe, Specter, and their ilk are often harmful to the interests of the party as a whole and certainly to the principles that animate the vast majority of Republicans. I think that a true RINO is one that has little or no loyalty to the party, and bends over backwards to go against the party, causing people to think that they label themselves as Republican only for political expediency. Bloomberg comes to mind.
I don't consider Arnold to be a RINO under that definition. He has been a friend to republicans for 30 years, and has been there for the party. I consider him to be a liberal Republican, as are Rudy Giuliani and Norm Coleman. Sometimes the choice is between a liberal Republican and a socialist, and I will always go with the liberal Republican. With Rudy we were rewarded with an efficient and good mayor who did not hurt conservatives because a mayor has little impact on issues like abortion. With Arnold, let's hope we get similar governance.
When the choice is between a true RINO and a Democrat, then I would analyze the race as though party labels did not exist, and figure out which person I wanted to win. If there is no difference between the candidates, then I would vote for the Democrat over a RINO, because if we are going to have Democrat policies, I would prefer they get blamed on a Democrat.
True Rinos that I have noticed were Weicker of Connecticut and Jeffords, before both of them changed parties, Bloomberg, Chafee, Gerald Ford, Specter, and a few in the House. Snowe worries me. In the Supreme Court, we have lost many judges, latest examples being O'Connor and Kennedy. There are a couple governors who act like RINOs, Ryan of Illinois being the latest example. Don't exonerate all RINOs just because we both support Arnold in this particular race. I'm sure he will make us both mad a few times in the next 3 years, but he is still preferable to Davis.