I think communication is key. If they have an idea, if they have questions or concerns, and especially if they are not happy. They should be able to effectively communicate what they are thinking/feeling regardless of the audience. I find that my friends who have strong technical backgrounds struggle with this.
I know this thread is about qualities but I'd say a big factor for remote people is their environment. Are they able to find the right environment to get work done?
Midinote