I noticed in my profile page that there is a summary of post ratings in the left column. It shows the number of each type, both received and given. Most of the types (like, agree, etc.) use green numbers, and two of them, disagree and optimistic, use black letters. It appears that "optimistic" must have a negative implication. I've received it and given it, but might have been using it incorrectly.
I thought that "optimistic" was a way of saying "I hope that works out for you", as in…
Original source: https://www.e-cigarette-forum.com/threads/ratings.967199/