A lot of it comes down to respecting the different ways of communicating that people have. You were mentioning engagement. There's a lot of discussion on what is or isn't appropriate.
In terms of social media research, where we are simply listening, we don't engage. There needs to be some understanding that not everyone wants to engage, and that if they do, it needs to be up front, with permission. As we normally would do with traditional market research standards, there needs to be permission before you pursue anything any further.