It's a vapid comment that lowers signal:noise, of course it should be downvoted.

Such comments are explicitly encouraged—see http://ycombinator.com/newswelcome.html:

Empty comments can be ok if they're positive. There's nothing wrong with submitting a comment saying just "Thanks." What we especially discourage are comments that are empty and negative—comments that are mere name-calling.

"Are ok" is not the same as "are explicitly encouraged". They are tolerated would be more correct. Also we cannot mindlessly follow a static HTML document.

I mostly a lurker of hacker news, do the see the scores as you gain more profile karama?

No.

What?

http://i.imgur.com/S0e14ml.png

You see your own points, not others'.

Pretty sure that was the question being asked. He wanted to know if/how mikeroher knew he hadn't been downvoted.

Since only I can see it, at the moment, the comment has 7 points.

Possibly they had. Possibly went gray for a time, indicating that its score was non-positive. Then it got upvoted, bringing it back to being positive.