As the GM, it is your responsibility to shut down abusive player behavior. If you run a game with close friends, you already do this, custom-tailored for them. You don't have to be hyper-alert to the players' reactions to things, because you've known them for a long time, and they're still playing with you. They've known you for a long time, too, and they know they can talk to you if something at the table makes them uncomfortable.
Gaming with acquaintances and strangers is another story. If you ever go to a convention or run games at a library, games cafe, or friendly local game store; you need to be more alert.
As responsible GMs, we must acknowledge that everyone is at risk for abusive behavior, and we are all good at noticing and controlling behaviors that make people like ourselves uncomfortable; but it takes heightened awareness and empathy to notice and respond to behavior that could make people different from us uncomfortable.
For instance, if you're thin, you may not notice fat shaming at your table. If you're a man, you may not notice a scene in a game that makes the women around you uncomfortable. If you're Jewish, you might have to pay special attention to make sure the table doesn't make a Christian uncomfortable.
The good news is that roleplayers and especially GMs get a lot of practice putting ourselves in others' shoes. Human empathy is "thinking in character" -- except that the person across the table from you is the character. You have the skills. You just have to activate them.
This is not about being politically correct, but about making sure everyone has the best time at your table. That's how your GMing is evaluated, in the end: How much fun did everyone have? If one player out of the four at your table is uncomfortable because half your D&D session was spent in a Faerun cathouse making caricatures of women and sex workers, and you didn't notice because you're not a woman; you only did a good job for 75% of your players. Even if the other 3 players had a blast, 75% is a C. Nobody wants to be a C-level GM. You don't have to be politically correct; you just have to be sensitive to the people at your table.
- Behavior at or near our table is something we GMs have authority to address.
- It takes special attention to be alert to behavior that could bother people different from us.
- Failing to notice and address behavior that makes our players uncomfortable is bad GMing.
- We must not allow that kind of behavior while we have the authority to stop it. #NotOnMyWatch (thanks to Heather Stern for the hashtag!)
You don't have to be a social justice warrior. You don't have to advocate for anything. You just have to do your job as a GM; and the most important part of your job is making sure everyone is comfortable and having a good time.