The worst part is downvoting someone without expressing why you did it. For example :

This is spam. Downvoted.

Most of the time people seem to just don't care about how someone else feels when gets downvoted. In the case of an article this gets more frustrating because there was effort to do it, document it and other things too. Even if the article is not what you think of "cool" it doesn't mean that it doesn't deserve an explanation on why it was downvoted. Some might say: This is the internet, democracy etc... Democracy is also getting annoyed when someone thinks of you like a "nothing". Other times, someone might post something that he doesn't like, only to see if others feel the same too.