As far as I can tell, there is no provenance, chain of custody or anything else with these samples. I had a brief conversation with Richard Stubstad in which I asked questions about how the samples were obtained and how and why he thought they were genuine. His answer was basically that at least two of them were 'vetted' beyond question. I replied that I thought that all of it. in the end, was simply a collection of storries. I was hoping for a scan or something from an actual lab to look at but that was not to be. I think this was back in October or so and occured on Robert Lindsay's blog.
While I don't think any respectable peer-reviewed journal will publish "Bigfoot has human DNA," I do think there are a number of not-respectable journals that would, and to them the provenance might matter. Of course, as you say, the stories of how they were collected are just stories. One possible exception is the sample(s) which came from the "habituation site" in Kentucky...the so-called Erickson Project. Those folks supposedly have video to back up their story that the specimen came from a "bigfoot", but so far the "vetting" of that footage has not been done, at least not publicly.
The place of origin of these samples may also become an issue. I have suggested that to make a hoax more believable, one could first collect samples from an extended human family from an isolated tribe eg the Hupa. Then one would carry the specimens around the country and mail them in to the lab from various locations. Alternatively, the lab could be in on the scam and simply represent the specimens as having come from various locations. In my scenario, I would not include, on my list of collection sites, the place at which they were actually collected, in case some enterprising journal editor decided to check on the tribal DNA there.
This scenario could create the illusion of a
couple dozen widely-separated but closely-related "individuals", sworn by 'footers to be phenotypic bigfoots, whose DNA looks to be human, but who have sequences which are not in GenBank. Statistically, if one were to (wrongly) assume randomness, this would be a very unlikely event. Voila! Bigfoot is human.