Unlike most rules of evidence which are drawn along pretty definite lines/boundaries, this subject of "consent" opens a door involving "intent" and that can lead to just plain old "speculation," so once again I'll offer URL's to various pages and try to cover the subject that way.

A New Jersey appeal involves the scope of questions a police officer may ask an occupant of a car that is stopped for a motor vehicle violation: read about it here

Some of the intricacies involved with this subject can be found here

This URL deals with deceit by the badges to conduct a search and the fact the black robes have ruled that unlike a Miranda Warning, you don't have to be warned about any deceit by the "protect & serve" crew

This URL covers evidence found by non-badge wearing parties and reported to the badge wearers and the way any possible illegality involved is gotten around at your expense

Can your girlfriend give consent to search your house? That depends

This URL covers a variety of issues dealing with who can/can't give consent to search