A republican becomes a RINO when he/she institutes or supports actions that are distinctly unconstitutional.
Providing support to, or even tolerating a RINO, only legitimizes their unconstitutional activities.
But it's even worse...
Leftists are blatantly un-Constitutional, and their positions are unattractive to the undecided American. The RINO is not quite so blatant; often they sacrafice the Constitution for some temporarily-perceived "greater good" or for some set of generic morality. This position erodes the support of Conservatives, whose steadfast support of the Constitution begins to look unreasonable to the short-sighted undecided American.
Thus, RINOs are responsible for the erosion of the respect for the Constitution.
No, RINOs are not good for this country.
Words and terms have specific meanings; meaning set in stone and no, you may NOT purloin any word and phrase and then make up your own definition for it.