Personally, I think Rand Paul would be great, but your point here is, well, pointless.
Jesse Helms, Strom Thurmond, and Ronald Reagan all used to be Democrats. I doubt anybody would suggest that they were trojan horse liberals, like some of the left-side-of-the-bell-curve types here on FR have been suggesting about all former Democrats lately.
Indeed. One of those most outrageous lies being spread by the Rand Paul supporters is that Trey Grayson served as a delegate for Bill Clinton at the DNC convention. That is a completely false, outrageous lie being spread by the Rand Paul supporters, and is quite telling as to their character and/or their ability to understand basic fact and are willing to just slander someone and treat them like garbage for no other reason than they are just the other candidate, and should be swatted away - like a fly.
Back in the 1940s, Ronald Reagan was certainly a liberal Democrat. Listen on youtube to speeches on corporate profits and his endorsements of Truman, Stevenson, Humphrey, etc.