So, they were mad at you. So what? How would anybody know whether that mother would end up forming a chapter of M.A.D.D. (Mothers Against Driving Drunk) or something like that? That one photo that they thought they didn't like could end up being the poster picture for her whole crusade.
Yes, I know. Grabbing at straws. The idea is valid, however.
There were a couple of times when my Congressman stepped out of the room to take a phone call or moved over to a corner of the room to have a private conversation. I watched where he went but didn't follow. I figured it would be bad form. There's nothing wrong with keeping an eye out, though. Just as in the hypothetical above, "What if?"
If an arguement broke out or something happened, I wouldn't hesitate to step in if I could. It would be news. Right?
Here I go grabbing at straws again, making a hypothetical: What if that photo was of a guy crashing the party, making trouble and harrassing the Congressman? That could be evidence in the Congressman's favor. Couldn't it?
Hypotheticals aside, my point is that, as a documentarian (an event photographer or a journalist) you never know what could happen. As long as you are polite, follow established rules of ethics and obey the law, it is your job to document what goes on.
One of my other pass times is sleight of hand magic. Coin tricks and stuff.
In learning magic, there is a concept called "The Honesty Hangup" that you have to get over.
Some people have the tendency to look guilty when they are doing a trick. If they are palming a coin, they'll hold their hands too stiff or will hesitate in making the "steal." That telegraphs the move to the audience and spoils the trick. It takes time to get over that feeling of guilt when you are ostensibly saying, "My hand is empty," all the while, you've got a coin in your palm.
I propose that there is a similar "honesty hangup" when people are learning documentary/journalistic photography. It just takes time to get used to the idea of photgraphing people who aren't asking you to take their picture.
I'm a pretty good magician. Not great but I can hold my own. It would be easy for me to use my magical skills to rip off nearly any cashier if I wanted to. In fact, a couple of the schticks I do are about how to catch a crook and they highlight techniques that somebody could use to rip somebody off. However, I would NEVER try to pull a rip-off in real life. First, because I'm not a crook and, second, because I value my reputation as a magician. I want people to come up and ask me to show them "that trick where I steal a coin from somebody's pocket" and not shy away for fear I would try to pick their pockets.
The same thing goes for photography. Your reputation is valuable. You want people to hire you for gigs or you want magazines and newspapers to pay you for your work. You don't want people running away from you every time you pick up a camera.