As a native speaker of German, perhaps you can shed some light on the connotations of the two possible words for bad actions, here. Marx would like to know. However, be that as it may, I'll give you that I think we may both have missed the mark on the best etymology of boschaft. What you do to your servants and kids, but they daren't do to you. Our English baste or lambaste is from the apparently-related Old Norse beysta, to beat.
Nothing subtle about it.
Which is what you seem to be suggesting. Finally, I wonder if there is be a punning connection in between the words raffiniert and boshaft, which sort of thing I wouldn't put past Einstein. Straight is the gate which leadeth to Heaven. These contrasting ideas must have been continuously in Einstein's mind from 1907 to 1915 and onward. The somewhat ironic thing is that Einstein's god, the god of Spinoza, aka the Universe, really is bent.