I can think of a few that fit that category. It was one of the first things I noticed coming back. I would have the 1st comment on a new submission, then 2 or 3 of the same old usernames would come along behind me, leave an lol, or something equally as lame and never upvote mine or anyone else that had subsequently commented. Personally I get what I need, but its easy to spot the point w**res. I may miss an upvote here or there because I'm moving too fast, but most of the time when I return to answer a reply I catch it. There are a few I refuse to upvote anymore because of this, and I will not comment on their memes even.