Some apps push data into the cloud without asking/having an option. For me this was Screens VNC, which synced semi-confidential information across my two computers without asking (all my bookmarks, except for the SSH/VNC passwords).

Arguably the external IP, SSH port, SSH username, internal IP and internal username of my client's confidential computer are only "security by obscurity", but I'd still rather have everything on my hard drive only by default.