I think the other question pretty much answers your question.
Most of the people that replied seem to use favorites like bookmarks (and I do as well).
So if you treat favorites like bookmarks, then by favoriting a question, you're telling the asker that you want to be able to refer back to that question in the future. That could be because there's a stellar answer you want to keep as a reference, or if there isn't a good answer yet you would be saying you're also interested in the answer. Or, it could even mean some people have unfinished business (examples given were wanting to vote when the daily cap has already been reached or wanting to revise an answer later).
Conversely, if your question doesn't have any favorites, than everybody who has visited it has already gotten everything out of it that they think they are going to get. That's not necessarily bad.