None of this stuff exists anymore. The unions are in bed with the company and whatever the company says the unions will do nowadays. Pilot unions are not involved in hiring anymore, and while some check airmen and CP's etc sit on the hiring/interview board, they have a lot more on their mind than researching the background and career choices of whomever is in front of them. Somebody stated a few posts prior about word of mouth...that is basically how people are blacklisted these days, but even then, that word of mouth has to wind up in the ears of somebody who directly controls pilot hiring.
Just don't be an @$$hole, come to work looking to better yourself and the lives of those you cross paths and you'll never have any problems. People who do choose to be jerks will eventually be hit with that freight train of bad karma at some point in their career/life.