NSFW search to see them: twitter.com/search?f=tweet…
Other bots target accounts based on the username.
Most of the accounts are old. From 2011-2014. As far as I remember it was much easier to create accounts back them. I don't know if they are old spam accounts or hacked and scrubbed accounts.
They have nearly no followers.
Few Tweets (<20).
50-100 Favs per account.
5k en, 1k es, 1k fr, 500 ko, 500 pt, 300 it, 300 pl, 260 de, 230 hu, 200 th.