How can I tell if GuestSpy is on my phone?

GuestSpy is not a virus and must be deliberately installed onto the Target device directly, with a unique set of steps and configurations. It will not perform any functions that were not configured by human intervention. However, it does not install any visible program menus, folders or icons (iDevice (iPhone, iPad, iPod Touch) version can choose to Hide/Unhide the icon for access). Once installed, it may only be accessed or uninstalled by equally deliberate human intervention.

You should not let anyone that you do not trust access your device.