"Although Dean Walker (Trejo's character) never says he's an Indian, a few things make the identification clear. One, with his hair in a ponytail, he looks like an Indian."
Over the past forty years or so I have seen all kinds of men from practically every ethnic group imaginable who have worn their hair in a ponytail. That a fairly well-known Chicano character actor sports a ponytail in a relatively unknown movie is hardly a clear indication that he is an Indian.
"Two, he cooks venison stew."
In America, more non-Indians (primarily white) cook venison stew on a regular basis than do most Indians (even those Indians who are reservation-based) as MORE white Americans engage in deer hunting than do Indians.
"Three and most important, he performs a smudging ceremony to help cleanse Sherry."
It is indeed safe to say that in the United States and in Europe more wannabes, New Age devotees, pagans, witches, warlocks, Touch the Earth-influenced environmentalists, and even some goths with phony tribal leanings, smudge with sage and cedar than do most Indians as there are far more of these people around than there are Indians. Even a lot of non-Indian ex-cons who have embraced Indian spirituality while in prison smudge regularly and probably engage in this practice more than do Indian people. In 1995, I lived in an apartment building where a white ex-convict nearly burnt the building down while smudging.
First, it's clear that none of the traits I listed (ponytail, venison stew, smudging) proves he's a Native. Many non-Natives indulge in these things too. But it's the combination of traits that matters, not each individual trait. Anyone who qualifies on all three traits is likely to be an Indian.
Let's do some math. Suppose there's a 79% chance each trait is possessed by a non-Native and a 21% chance it's possessed by a Native. (The reason for choosing 79% will become clear.) Spelling it out:
Does this mean there's a 79% chance a person with all three traits is a non-Native? No. To determine the combined probability, we multiply .79 * .79 * .79. Result: There's only a 49.3% chance a person with all three traits is a non-Native. And a 50.7% chance he's a Native.
Location, location, location
Let's note that Sherrybaby takes place in a run-down section of urban New Jersey. It seems like a place where you'd find the working poor, homeless people, gangs, even mobsters. It doesn't seem like a place where you'd find touchy-feely New Age types with crystals and candles.
If you factor in the location, I'd say you could safely lower the percentages a few points. So let's assume the numbers actually look like this:
Result: .76 * .76 * .76 = 43.9% chance the person is non-Native.
The addiction factor
It's an unfortunate fact that Natives suffer more substance-abuse problems per capita than other ethnic groups. If a person has an addiction, as Walker does, let's assume there's a 97% chance he's non-Native and a 3% chance's he's Native. We multiply that with the previous result:
.439 * .97 = 42.5% chance the person is non-Native.
These calculations depend on how accurate the initial assumptions are, of course. And there's no easy way of knowing that. Maybe there's a 95% chance someone with a ponytail is a non-Native. But maybe there's only a 63% chance someone who smudges is a non-Native. I think my assumptions are reasonable.
Trejo plays Indians
There's also the meta-evidence of Danny Trejo's career. One, he's Latino, which means there's a good chance he has Indian ancestors. Two, he's played an Indian or a part-Indian several times.
Why would you cast Trejo in the role if you meant Walker to be a non-Native New Ager? When people see Trejo on the screen, they think "Indian or part-Indian or Latino with Indian roots." They don't think "non-Native who indulges in New Age practices and coincidentally resembles an Indian."
Finally, most reviews of Sherrybaby didn't say anything about Trejo's ethnicity, but at least one did:
For more on the subject, see The Best Indian Movies.