Honest question: As an observer, when should I feel comfortable interjecting? Things like "if the afflicted party looks uncomfortable" seems rather vague, and just because I am offended doesn't mean the person receiving it is offended (I've known this to be the case). I'm honestly interested in knowing the best way to gauge when I should act without insulting people that are offended. I'm referring to the non-obvious cases, of course. Unwanted groping is fairly obvious, for example. However, agressive flirting without a clear sign?
Approaching strangers can be difficult or awkward but here's a clear step at least:
Step in when it's one of your friends doing the harassing. Let them know they're being immature and inappropriate. People respond a lot more when it's someone in their peer group.
I'm sure a lot of people have let a lot of stuff like the above slide because "Oh that's just FooBar. He's always like that".
"As an observer, when should I feel comfortable interjecting? "
When someones health, life or well being is on the line. I have seen too many women starting / acting scenes just to make some white knight to intervene. There was research where in public woman was being assaulted/abused by man and everyone intervened. Then they switched it around - NOONE CARED.
Besides, feminism was claiming how strong and able to defend themselves women are. So by interjecting you are being SEXIST.