I have never heard a person utter the word “inscrutable,” although I’ve seen it in print on rare occasions. It’s one of those oft-overlooked gems, like invidious. And while there may have been some sort of racist connotation attached to the word once upon a time, I am confident that age is long past.
For me, the word means whatever the OED tells me it means 
Oh, good one!
I’m old enough to remember the link to Asian stereotypes.
Recently, I’ve seen it applied to some business situations, usually in a negative way. “It is suspected additional lay-offs will be announced this week, but the CEO appeared inscrutable when he gave a brief interview on the merger.” The poker face execs have when callously determining the fate of the honest workers, that sort of connotation.
This thread is 4 years old. We don’t generally revive things that old, but since you commented several other people have joined in. So I’ll answer the question.
In parts of the US Midwest, there is/was a superstition common among Catholics (and since spread to the general culture) that burying St. Joseph headfirst in the front yard brings good luck when trying to sell the house. Since any house-seller wants a quick sale at a high price, lots of people do it. Some of whom do sell their house quickly, which reinforces the supposed effectiveness of the ritual.
I suspect the superstition dates from the 1950s-1960s, but it was still prevalent at least where I was living as late as 2010 when I wrote that post.