Aren't Democrats for Mc Cain merely Republicans who switched over to the Democrat party in the first place?

Since Hillary lost the Democratic Primary, I see all of these disgruntled Clinton supporters declaring themselves, Democrats for McCain. Ha Ha Ha. I find that very funny. Who are they trying to fool. A true Democrat would never vote for a Republican, regardless or race, color or creed. After Bush's two terms in office, a lot of Republicans switched over to the Democratic Party. After the Democratic primary it has become quite obvious that the so-called Democrats for McCain are merely Republicans who refuse to vote in a minority as president. That's my take on it. What do you think?