Ok once I had problems with spam bots commenting my posts with ads and links but I installed the reCaptcha plugin for wordpress and forgot about it. However these days I have problems again. This is one particular IP that is able to break through the validation! The IP is 22.214.171.124 and I really would suggest to you to add it to your ban list. I will do it for sure! Today I had like 50 comments on a post, all got in approved !