With the controversy growing about privacy of users about Amazon shopping lens, Canonical has finally taken a step that will perhaps make users happy. The shoping lens which is currenlty in development phase, will have a setting that will disable online results from Unity dash. This will disable the shopping lens and also other online results, such as Gwibber, photos from Facebook etc.
The shopping lens feature is currently in the 12.10 development branch and undergoing extensive testing; thanks to Nick Skaggs for rallying folks around this additional testing to assure quality.
You will be able to disable the feature if you wish. There is work going on to have a toggle switch in the settings to disable it. Note that this will affect all online searches (e.g. Gwibber).
Here is a screenshot:
The developers are now working to encrypt the search traffic which will be ready by 12.10's final release.