And such claims are not always false.
A recent memorable example was that conservative "witch" in Delaware with enough Tea Party support to defeat her RINO opponent in the primary, only to loose the general.
The truth is, we are a "right of center" country, overall, but just barely, and in many states or districts RINO is the best we could ever hope for.
So, are we better off with RINOs or Democrats?
Answer: if our leadership is truly conservative, then a few RINOs will help more than hinder.
As for replacing "Republicans" with "Conservatives", they should be more-or-less the same thing, and generally are -- certainly as compared to more Liberal-Progressive Democrats.
The biggest problem then is: how to find the most conservative Republican candidates possible for each district/state, and then after elections hold their feet to the conservative fire?
The answers are: measurement, discipline and leadership, not necessarily in that order.