The Internet of Things doesn't inherently have to be an Internet of Telemarketers and Snoops. It could be made of personal devices which keep the users' personal data to themselves, while receiving published data from businesses.

The only practical way to ensure the devices don't snoop is if their software is free.

Many baby monitors (internet-connected cameras, really) have been left vulnerable to snooping by unknown third parties.

The immediate cause is bad design, but the root cause, in some cases, is routing the video through the server of a company that shouldn't be trusted with a view of the inside of your home.