My definition of a RINO is someone whose political identity is sufficiently defined by his ability to "work with" Democrats that, despite running on the Republican ticket, he would rather undermine the conservative cause than have it cripple the Democrats and render useless his ability to "work with" them.
One possible rule change in Congress which would IMHO improve the quality of representation immensely would be to only reveal how congresscritters vote on things after voting is closed. As it is, if a majority of congress wants various things, but only a minority really wants to go on record as supporting them, that minority can avoid having more people go on record as voting for it than are required to pass it. If some of the potential support for a bill was from people who want its supporters to actually go on record, and wouldn't reveal their support or lack thereof until after the close of voting, its supporters would have to guess at how many votes they'd need, and would be much more likely to cast votes that reflected their true ideology.
Actually, Congress has had a rule sort of like that for decades. Back when they used to pass pay raises for the sitting Congress (before they accidentally passed an Amendment that only allows them to give pay raises to the NEXT Congress!), it was always surprising to hear most of the Congress get in front of a microphone the next day and deny that they had voted for the raise. If no one voted for it, how did it get passed?
This is how they did it: A rider with the pay raise would be attached to a bill and the bill forwarded to the Speaker's inbox for action. At this point, a bill would typically either end up in committee or it would be called for a floor vote. However, when the bill with the pay raise rider was submitted, it would be allowed to sit on the Speaker's docket for 72 hours with NO action taken. The rule was that if a bill sat on the docket for 72 hours with no action taken, it was considered automatically passed and sent to the president to sign, which he typically did.
And, that's how it really works! So, when all those Congresscritters would find a microphone to deny voting for their pay raise (which was usually VERY unpopular with the taxpayers!), they weren't lying!! They just hadn't done their job for 72 hours!
Wouldn't you like to avoid doing your job for 72 hours an get a pay raise??