Funny story about jumpseating back in the day. I was jumpseating in the states from Alaska back to Louisiana. I flew for a small 135 operation in AK and we actually had jumpseat privileges on the majors somehow. So I go into the cockpit to meet the CA and introduce myself and he says, "Have you ever crossed a picket line son?" Me: "No sir, this is my first real aviation job." He says, "Well, I've got a list here, and if I find your name on it, you're not riding on my airplane." So he proceeds to get out his old list of scabs and went through the last names to check for mine. lol

And that wasn't the last time it happened. Had a couple other CA's that would take my badge and look at their scab list before signing it.