Try looking at the comments capsule and go into edit for that hub comment capsule. By default the comment will show up unless you have the "Comments must be approved before they appear" box checked. There are also some other settings like receiving an email and such. The approve button will show up even tho the comment doesn't need approval to show up. I'm not sure why this occurs but it still gives you the option to deny the comment, so I think its good idea that the buttons still show to give you a second option to approve them or not.
I have had to deny comments from spammers but I always get a email alerting me that a comment was left so I can check it later. That is by default also.