I think an upvote suggests agreement with the content rather than gratefulness for it. If someone has a wrong opinion, but people are interested in why, and he explains it, and they all upvote it out of gratitude, he might interpret that as agreement.
If a downvote implies something other than the opposite of what an upvote implies, it becomes difficult to interpret votes.
Would downvoting imply disagreement, then?
I think an upvote suggests agreement with the content rather than gratefulness for it. If someone has a wrong opinion, but people are interested in why, and he explains it, and they all upvote it out of gratitude, he might interpret that as agreement.
If a downvote implies something other than the opposite of what an upvote implies, it becomes difficult to interpret votes.