Its reality, there are several proofs.
Generally, are groups of people that in one or another way are making profits based on the use of bots.
I remember one big file of several GBs available at one well known poker forum, i didnt downloaded it, but shared a ton of info about a group of people using bot in various poker websites, (the most known wasnt in the list, but another ones with big number of players and traffic was in the list, and one of the most known too).
I guess is not so hard to code bots and put some servers to work, at the end, where is money always are cheaters and stealers.
Anyway, the rule will be play vs humans, play with a bot will be an exceptional case and poker sites that respect their players are aware of any bot or colusion, no one wants a successfull business turn into a dirty one, so i will not worry, but i have a youtube video when it looks like i was playing with a bot, i will edit this post and add the link if its not against the norms of the forum, just let me know in a reply please.