Since I added the possibility to leave comments on my blog-posts, I saw a big increase in spamming-attempts. But interestingly, these are not typical spams containing some medic keywords and an URL, no, they now write how much this blog post helped them. Only after the second time you read the comment, one will understand that it is a spam-comment. 

Here are some examples:

Sorry for my bad english. Thank you so much for your good post. Your post helped me in my college assignment, If you can provide me more details please email me. Welcome to my website : Something

Thanks for taking this opportunity to mention this, I'm strongly about it and I benefit from garden greenhouse structures this subject. When possible, when you gain data, please update this website with new information. I have found it extremely useful.
My site is on somesite>Something.

The cat-and-mouse-game continues...