In all fairness, this has been rinsed and repeated a number of times in recent history. Reagan was a true conservative, but was held back by a democratic congress. Bush Sr. just wasn't a real conservative because he raised taxes. Bush Jr wasn't a real conservative because well, he spent like crazy.
The Democrats do the same thing: Clinton wasn't a real "democrat" because he signed NAFTA and reformed welfare. Obama "wasn't real" because he couldn't end the wars, close GITMO or reform the finance industry. (a number of other items)
I find it helpful to at the very least split into social vs. fiscal conservatives. It is easy to be socially liberal and fiscally conservative, or socially conservative and fiscally liberal. G. W. Bush was socially conservative and fiscally liberal.
Of course you can split things much further than that; nothing really stops you from being an anti-abortion otherwise-social-liberal, but I really think failing to split out social/fiscal leaves you really baffled by who is aligned with who.
The Democrats do the same thing: Clinton wasn't a real "democrat" because he signed NAFTA and reformed welfare. Obama "wasn't real" because he couldn't end the wars, close GITMO or reform the finance industry. (a number of other items)