I practice this line regularly so that I can be respectful while still making it clear that I will not be consenting to the search. I've never had to use the line for real, but am fairly confident that I'm prepared to do so if the need ever arises. If their response is that they don't need my consent, then obviously I won't be getting in their way.
Agree. As it should be. As Ive said time and time again, a consent to a search is never required. Ever. Period. You can consent if you like, but why? And this is coming from me, an LEO. You have 4th Amendment rights, don't give them up. Unless it's one of the 4th Amendment exceptions (extended border, at the border, functional border equivalent), then the standard 4th protections apply. They are your rights to have, or to give up if you so choose. And as you state eloquently above, there are respectful....yet still solid....methods of communicating the above. Well stated.