SPAM comes in many forms.
The new trend I have been seeing is comments that, at first, appear to be legitimate. They are very complimentary and often flattering, but if you really look, they don’t say anything specific. “Wow, great post. This is the information I’ve been looking for. I will definitely be back.”
They will even use your name, but if they don’t say what specifically caught their eye, then they are spam.
If they are complimenting you on your theme, I would say they are spam. If there are similar or duplicate comments, they are probably spam as well.
Under the comment are several links: approve, spam, reply etc. Definitely mark them as spam and then Akismet won’t allow the IP address.
It takes a lot of work to keep ahead of them, but once you start to block the IP addresses, there will be fewer.