The majority on FR and other conservative sites use the term as I described. It is best to speak the language in the manner most people speak it. If you want to be a literalist, it would also imply that you mean the term RINO to mean a member of the GOP who is secretly a member of the Democrat Party. IOW, you will end up implying that you are a conspiracy theorist.
Cao was a RINO. Bloomberg was a RINO. People who would never embrace the majority of the REPUBLICAN beliefs, but run as republicans because it gives them an advantage.
Maybe the real republican in name only are those who claim to be a republican, but then insist that positions accepted by a sizable minority of republicans aren't republican positions.
Support for ethanol subsidies, unfortunately, crosses party lines. In 2008, when the republican platform called for an end of the subsidies, it was considered "stunning". Conservatives are much more likely to oppose the subsidies, but again the Republican party is not the Conservative Party -- the name is a giveaway there.
To label Santorum a RINO is to render the term meaningless. What party do you think Santorum would better belong to? "On the Issues" calls him a "hard-core conservative". On the major fiscal issues, he's conservative. On the major social issues, he's a conservative. On the major constitutional issues, he's a conservative. He has a few holes in that conservative armor.
Pro-life; Pro-marriage; pro-gun; anti-government-healthcare, pro-death-penalty, pro-vouchers, anti-progressive-taxation;pro-taxcuts, anti-illegal-immigrant.
Oh, but he favors ethanol subsidies, so he's a RINO. On the issues, he's probably got more conservative credits than Ronald Reagan. But he's a RINO, because, well because you say so, and RINO means whatever you say it means, because you are the Queen of Hearts.