Remember to retrieve your fluids!

I'm a reasonably law-n-order-type guy, but there is something creepily Orwellian (and Gattacan) about this, via Volokh Conspiracy:

Facts: Rape suspect walking on a street spits on the sidewalk. An investigator is following the suspect, and he collects the spit; a DNA test proves a match. Holding: No Fourth Amendment violation. Analysis:

[A]lthough the defendant had a reasonable expectation of privacy in his saliva (and other bodily fluids)...when he expectorated on to a public street and did not retrieve the fluid, he voluntarily abandoned that protection; he assumed the risk of the public witnessing his action and thereafter taking possession of his bodily fluids.

(Emphasis added)

As one commenter to the post notes:

I wonder about the scenario where the cops take a suspect down to the station, load him up with coffee and donuts, and wait for him to take a crap in the special DNA-collecting toilet.

I suppose the basic argument, once again, is that if you haven't done anything wrong and/or have nothing to hide, what is the harm in the police being able to scoop up your saliva, et al? I worry (not entirely facetiously) about the coffee and donuts scenario presented above, but also about, uh, let's call them "false positives." Yes, you may call me paranoid, but what if someone somehow gets someone else's genetic materials (and the possibilities here are endless, ranging from a good spy story to a porn movie plot, ask me about my screenplays) and plants them at the scene of a crime? Will we someday have to submit a spit/blood/mucus/urine/stool/hair follicle/s***n sample to get a driver's license or passport?

Given that we now inhabit a country where the Republican candidates for president don't quite seem to get that Jack Bauer is a fictional character, and the CSI's are all huge hits, is my scenario that far-fetched?

If it turns out that the government will require me to submit a s***n sample, may I at least make a request as to who collects it?

Perhaps there is a simpler moral here: it is rude to spit, urinate, vomit, or otherwise expel genetic material in public, and now you really don't want to do it (or at least use a trash can, you know, for plausible deniability).