I'm guilty of #5 from time to time. Only because of nervousness.
I've actually unbuckled my seat belt a few times and have been asked if I ever had it on. (Big no no)
8 ways to lower the odds of being ticketed when police pull you over
Reminds me of a seat belt debate I had with a sheriff's deputy last year.
I was driving my Thunderbird with the removable hardtop in place. I passed the radar running officer at the legal speed and he lit up his blues and pulled me over.
"I pulled you over because your seat belt isn't buckled", he informed me.
I showed him that the seat belt was in place over my lap and the shoulder strap was leading back to it's anchor point behind the seat.
"No", he said, "the shoulder harness has to attach to the roof or pillar of the vehicle".
As nicely as I could I explained that the roof was detachable and therefore there was no place to anchor the belt to the roof. He didn't believe me.
"This is a hardtop", he said, "it doesn't retract".
"That's right", I replied, "it comes off completely".
We then debated the design of the car for a bit and I asked him if I could demonstrate how the roof detached. I then got out and released the rear supports for the top and unclipped the front from the top of windshield.
Unbelievably, he wrote me a warning ticket for having an improper seat belt and went back to his cruiser.