I recall several cases where cops got their probable cause for a warrant by peeking in people's windows. So I make a point of using curtains. Drapes block prying eyes, but how do you block prying noses?

Git, Fido!
I guess the first, and most common, chemical sensor is the plain old dog. They've been trained to sniff out people, corpses, drugs, explosives, and no doubt plenty of things that haven't occurred to me. Dog noses are pretty sensitive.

Which is their vulnerability. They're so sensitive that they can be overwhelmed. A dog hit with pepper spray is a pitiful sight. But a less direct application works, too.

Next time you don't want some canine sniffing around your car, give it -- the car, that is -- a pepper treatment. Buy a cheap can of pepper spray and squirt your fenders, doorframes, hood, and trunk; Just walk around the vehicle spraying lightly. Be careful not to get downwind of the spray, and you'll want to avoid your car for a few minutes. Don't spray the interior. Rover will be hesitant to come near your car, and his detection capacity will be diminished.

This'll keep the damned cats from trotting around leaving pawprints on your windshield, too.

Misdirection
Of course, if Rover is busy sniffing some other sucker's crotch, his nose isn't in your private stuff. Give him another target.

Some marijuana activists prepared a "pot perfume" and hosed down a ferry with the stuff, cars and all. Made it impossible for the dogs to isolate a target for harrassment.

You'll have to sacrifice some precious weed to do this:

1. Put a pint of vodka into a blender.
2. Add as much of your herb as you can make yourself give up.
3. Blend.
4. Let it sit and steep for a few hours. Console yourself on the loss by consuming remaining vodka and grass.
5. Strain the fluid into a spray bottle, which can be found in any housewares section of any decent store.
6. Apply to the target.

Reinforcing the point
Maybe you heard that the FAA is telling people not to pack food in their bags when flying. It causes false positives in their bomb-sniffing machines. Those multi-million dollar exercises in rights-bashing don't work. About half the time, they don't detect test explosives that are there, and I've heard that two-thirds of their positives are false. Aren't you glad that Mineta is spending your money so wisely?

Fact is, those machines are dangerous because they also provide a false sense of security. They don't work, but too many travelers don't get it. The point should be hammered home.

Let's try the perfume trick again. This time, dissolve common lawn or garden fertilizer in water. Fertilizer contains nitrates, which what those machines are trying to sniff out. You're just going to give them something to smell.

Because of what you're going to spray, you'll likely want something more surreptitious than a spray bottle. Try a little bottle of nasal spray; empty the medicine, and replace it with liquid fertilizer.

Take it to department stores and spray all the luggage. Concentrate on zippers and handles. You don't need to soak and visibly stain the merchandise; just leave enough nitrates to be chemically detectable. Visit bus stations, too, and baptize travelers' gear. You can do this at airports, but you'll need to operate in the non-secured areas, before the checkpoints. Be aware of surveillance cameras. Just spray a casual puff of fertilizer into the air as you pass waiting passengers and their luggage.

Payback
Wouldn't it be ironic if everyone targeted Drug and Terror Warriors for cannibis and nitrate tagging, just to incriminate them, and let them suffer from the unconstitutional indignities they've laid on us?