Sittin in gg2 with the gang before for the first time in ages and about 3 rounds in a row headshots were not regestering big red marks on their faces with no dmg now at first i thought it may have been me or the other player so i jumped into another server not ga and found rego to be awesome i really dnt get it and rates were all good

The blood you are seeing is client-side, your client thinks you hit them in the head so it paints the blood on their body, it then verifies with the server that you did in fact hit the person, at which point the server says that you didn't, but the blood is already there and doesn't get removed. The server says your shots missed, its not dodgy rego, its just a badly coded part of the source engine.