Admin impersonation?

Hi All

I have been having an issue with splogs but I'm following some recommendations and the numbers are not that bad. the problem i am having right now is that some splogers are able to write blogs that reflect on site wide activity as posted by Admin. Other users come and see that the admin has done something and go ahead and read it thinking that we did it. this is a significant security issue as they might be lead to reveal important personal information.

How can i prevent this from happening?