You know you are blacklisted when you send resumes they call you for an interview all seems to go well and they even give you their number for you to call them back in a couple of days only to get voice mails, and never again hear from them after you leave endless messages.
The same event happens at every job you go to and suddenly you get lots of spam mail with the subject words
"blackball", " blackie", etc, etc.
Take it from me I know first hand.
I have been blacklisted, filed official EEOC complaints visited lawyers and been told off the record "they can keep you off work forever".
This is the free country we live in.