The term is misused to mean something other than what it actually means. Mostly, it is used to indicate a personal dislike for the person being labelled, and as an easy way to attack an unfavored politician without having to actually discuss issues or think too hard.
There's not much point in having language if people start redefining terms as it suits them. Might as well live in wonderland.
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.