What's in a name?
If by conservative we mean the adherence to constitutional principles of limited government, fiscal responsibility, national sovereignty, and a foreign policy of avoiding foreign entanglements. Preserving the Constitution, the freedoms it guarantees. . . then John McCain is not a "conservative".
Conversely, if by conservative we mean the adherence to mean political rhetoric, Keynesian deficit spending, allegiance to sundry supranational agencies, and a foreign policy of complete interventionism. Undoing the Constitution, and the freedoms it guarantees. . . then Dr. Paul is not a "conservative".