Where did your buddy get his information? AFAIK, Police can only legally search your vehicle if you are being detained based on probable cause of the commission of a crime or if you consent to it. A traffic violation is not reason enough to search your vehicle, neither is refusal to grant permission to search. If you are not being detained then you are free to go and they cannot search.
No offense, but your buddy is full of ****......Unless you give consent, the police cannot search your car unless it is incident to arrest or if they have a search warrant...and oh, a "Game Warden" can't come into your house anytime they want (heard this one a million times too).
I have volunteered the info a couple of times that I had one in the glove box when asked for insurance card. I have always been told thank you for the info. Wait till I get to the other side and open the door before opening the glove box and all was good