Thus far, everything I have replied to I have read. Not only have I read it, I have only upvoted it if it met two criteria;
- The post personally interested me
- The post contained enough information to add valuable content to the community in some way
That said, many people are "Facebook trained" and blindly hit "like" (in this case upvote) and comment "Ha!" or some other conversational response. If the motivation is income, well shame on them. If the motivation is simply that's the way they interact conversationally, perhaps engagement can help them to become more eloquent in online communication.