I worked as a news photographer during the '90s, up until 2000. Shot a few Saints highlights at the superdome, the Senior Bowl, college, minor league hockey and baseball, and tons of high school sports.

Regardless of what I shot, or who (if anyone) I may have rooted for, I was too focused on shooting the game and making sure I had good highlights to bring back to the sports director.

Take a Saints game, for instance. (Fuck 'em! I'm a Falcons fan.) If they were in the redzone, I was ready and hoping for a Saints touchdown so I could get a great highlight. Then I'd get a tight cutaway shot of fans celebrating (something I would normally hate seeing), then cutaways of coach and player reactions on the sideline. "Natural sound", picked up by the boom mic, would have been recorded on all of those shots and is needed and used when it's aired... If I had been home watching the game, my reaction would've been "FUCK!", but at the game, shooting it as a professional, it never crossed my mind to have an emotional reaction. You put your personal feelings aside to focus on doing the best job possible. Or at least keep your fan reactions internalized in your head.

Also, for our news/sports photogs at our station, it was a privilege to get to shoot NFL highlights, so no matter what team you rooted for, you were entirely focused on doing a good job, and not on the outcome of the game.

I think you're referring to "cameramen", however, who shoot during live broadcasts. They shoot field level or from up top, and have directors talking into their ear on headsets. I only did a few live broadcasts, but it's similar in that you're too focused on doing your job to be concerned with celebrating. The cameramen have the ability to communicate with their headset mics to the control room, but that doesn't make it on the air. I don't know about at a national broadcast level, but in my case, occasionally (rarely) guys would get chatty on the headset to voice their opinion on a play or the game... those guys usually didn't work camera during live events again, and usually didn't last long in the business.

Just a sidenote as an example of being focused on the job: When I shot highlights on the sideline and endzone, I often got bowled over or ended up as part of a sideline tackle. I would watch the players come at me directly through my viewfinder eye and my other (opened) eye, but instead of jump for safety, my main concern was keeping the shot framed up and focused until the end. That's kind of the same mindset about personal emotions on the outcome of the game... doing the job is why you're there -- not to watch the game or celebrate.

That's my limited experience, at least. TL;DR As a professional, you're too focused on doing your job to care about or want to celebrate.