I am gonna answer, however I am not 1000000% sure I am right. There is ALWAYS a possibility for things to be done. I do not believe that they can see what blood mod you have on, I believe it is just like a custom skin, they have to have the file and so does the server in order for them to be able to see it. So My answer is no, but maybe others might wanna comment as well.

-Sniped