Don't forget that changes in the blood pressure of the inspector could cause higher or lower pressure on the nerves within the thumb, creating discrepancies in the perceived pressure within the tube.

Just a comment on the thumb test. I met someone on a group ride who always checked her tires by thumb before riding. At the group ride, she was down to about 70-80 psi because she had been checking like that for months. Since it only lost a few psi per week, her thumb couldn't tell the small changes. Like the frog in water being brought to a boil.

One way to make sure you don't lose pressure when you're pumping tyres is to use a presta adapter. Costs about a buck and should be available from most lbs.

This thread is really splitting hairs.

At least it's a lot cleaner and less offensive than splitting hares.