I've juste seen some strange links on "Recent actions", and I was curious to know why very old articles like "Codeforces Beta Round #57 (Div. 2) " were on the list. The response is simple: Some people use old articles to hide comments for increase popularity. Here, we have Soheil96 who added two minimalist comments ":D" or "like.", and used multi account (or asked friends) to give him positives votes.

On recents articles, thoses kinds of comments will have a lot of negative, but hidden between very old comments, the comments conserve positive ratings.

Edit: http://codeforces.com/blog/entry/1337#comment-130575 http://codeforces.com/blog/entry/1337#comment-130576