Let me start by saying that this is my own personal opinion/review of this product. I have to say that in the short trial period that I used the Anti-Spam by CleanTalk plugin for my WordPress website I have been very pleased. I used to have to wade through 30 or more spam comments per day to decide if they were real or not and send them to my spam folder. In the seven days that I have used it, it blocked 288 submissions from my website. I did get a small handful (less than 5) in the seven days that I used it, but as I marked them as spam, the plugin added them to their list which as I understand it, increases the power for others.
I fully recommend this product. At $8 per year for one website for the service compared to the time that it saves is WELL worth the money. That is less than a dollar a month. If you run multiple websites, the price gets cheaper per site the more you have. For me to give up one diet pepsi per month for this kind of protection, I can handle that.
Visit https://cleantalk.org/help/cleantalk-spam-firewall for more details. You can get a 7 day no obligation free trial to see for yourself. You do not have to enter any credit card information to sign up for the trial, so what are you waiting for.