When I first started using remote control tools, we were specifically forbidden from doing this. The guidelines were very clear. We had to ask permission to initiate the remote control - we weren't allowed to say "this will pop up and ask you to confirm, please just press yes". We were to instruct the user that they must monitor what we did at all times - they weren't allowed to leave their desk for the duration of the control. And we were required to disconnect before ending the call and advise them that we were disconnecting.
It's a whole bunch less strict now, but I still balk at saying "just press yes".