I get the error message `Unable to mount host` when I try to connect to a SFTP/SSH site as backup destination as superuser (root). What's wrong?

Q:
I get the error message `Unable to mount host` when I try to connect to a SFTP/SSH site as backup destination as superuser (root). What's wrong?

A:
Probably your remote destination is not yet added as trusted machine for user 'root'. Nautilus asks regular users when connecting to servers for the first time whether to trust the remote machine or not. The confirmation is only valid for a certain user. To connect remotely as superuser you have to add the remote machine to your trust pool. Open a terminal and type the following:
sudo ssh <username>@hostname.

You'll be asked whether you trust the remote machine or not - answer with yes. You should now be able to connect to the remote destination in (Not so) Simple Backup configuration GUI.