RINO has never been a useful acronym, as The Republican Party has always had liberals.
CINO is arguably a better acronym, but I think cafeteria conservative is a more useful term. It pegs Bush43, a big spender weak on immigration, but strong on cutting taxes and national defense.
I would agree that CINO makes some sense and is accurate, but I think “unreliable” or “shaky” conservative gets the message across.
RINO was for a time useful, but it is useless now because of over use. No one owns the word so anyone is free to apply it as they want to, but It was not intended by those who crafted the term to mean anything other than a Republican who advanced by trashing other Republicans. Thus, the term, Republican in Name Only.
Since these were almost always moderate and liberal Republicans who did this, a lot of single issue conservatives - especially single issue pro lifers - started using the term for Republicans who went the wrong way on that issue. But this is misleading since the quintessential RINO is John McCain, and he is (technically) pro life and I think so is Lindsay Graham.
Both McCain and Graham are much much more likely to curry favor with liberals by trashing other Republicans or even conservatives than say, Rudy G, who while disagreeing with pro lifers, has never gone out of his way to antagonize the conservative base on a regular basis the way McCain and Graham do every time a camera is rolling it seems.
It’s an interesting conversation, and I don’t think RINO will ever mean what it once did - killed by over use and mis-use.