There have been plenty of "users" asking "questions" which turn out to be spam and advertising. Some examples include:

![advert 1][1]

![advert 2][2]

These are blatant advertising, and I suspect that a bot could be to blame. I'm requesting an addition to the account creation process which requires verification that you're human.
  [1]: https://i.sstatic.net/gJvxq.png
  [2]: https://i.sstatic.net/hdElv.png