what all is bad about having a user be a member of the nobody group?

and is there anything special about the nobody group so that this user would still be unable to view (via an ftp client) any files owner/grouped by nobody. (ex: cuteftp or through filezilla). b/c at the moment i have a user who can't even see the files and directories owned/grouped by nobody; much less edit them. however, this user can log in through a terminal and edit and create in these files/directories owned by nobody. why is this? thnx for the help again guys.