Leftists often parade as rightists, especially among libertarians. But they let things slip.
The hallmarks of a consummate leftist are:
1. He’ll rabbits on about the evils of McCarthyism, when Joe McCarthy was an American hero.
2. He’s wont to compare “bad” countries—the lefty usually chooses Israel—to apartheid South Africa, showing a knee-jerk leftist sensibility and absolutely no clue about apartheid.
Please add your litmus tests for leftism, which, naturally, includes most conservatives.
UPDATE I (4/20):
3. Hating on James Burnham (and his ilk) under the guise that he was once a Trotskyist. Not all former Trotskyists (like Michael Medvend) are worthless and worse. Burnham was on the wrong side before converting to Old Rightism, but in “Suicide of the West” and “Managerial Revolution” he came to embody the best of Old the Right. Monumental works. Of course Jeet heert, editor at the New Republic, would hate Burnham. All lefties do.
I still hate James Burnham. https://t.co/KNTqQMWq4w
— Justin Raimondo (@JustinRaimondo) April 20, 2018
UPDATE II (5/14):
That’s another thing that distinguishes left from right libertarian: the right kind (all 10 of us) likes monarchy, doesn’t cheer the prospects of a left-wing, tacky, radical feminist, Megan Markle, dismantling it. Read “Mobocracy Vs. Monarchy.”