Youhosting.com offers free unlimited reseller hosting(as they say) with a limitation that you can only offer 10gb diskspace and 100 gb bandwidth to your clients. It seems too good to be true. I joined them and without even sharing my site, users started to join my site. I then shared my site on social media, I was getting 2 to 3 signups a day. After almost a month, I googled my site and found one of my subdomain(created by a user) was listed in blacklist in cleantalk.org with lot of people reporting it as spam. I then searched site:mysite.tld on google and found that almost every subdomain was involved in spamming. I then signed into my youhosting to see who uses my website and found that leaving two all were spam bots. I have cancelled my account with them almost three months ago, but whenever I start a forum on forum.mysite.tld(just to test), before I can even complete setup of forum, dozens of spambots register on forum and post dozens of spam posts. So my advice to all persons who are thinking to open an account with, STAY away from them. Either they have very simple captcha(it is) that spambots easily manage to register or they have a lot of spambots, so when someone registers they send all the spambots to register on that site. As they say you get what you pay for but they are not even worth it to spend even a minute with them.
Yes CleanTalk useful service against spam bots, they have modules and plugins automatic protection against spam sites invisible to visitors without captchas, etc.