Just as an example, there are many ways to speak in bad faith: They say something they know is wrong so you correct them, then they take offense. They then leverage this perceived (by everyone else) offense and use it to gain some sort of advantage (over you, or systemically).

In contrast, talking in good faith is saying something they believe is true. Maybe you correct them or maybe you don't, but in the end they're just trying to talk to other people.