If you're talking about unit 731 and the nazis then there was very little, if anything, scientifically valuable there.
They had terrible research methodology that rendered what data they gathered mostly useless, and even if it wasn't, most of the information could have been surmised by other methods. Some of the things they did served no conceivable practical or scientific purpose whatsoever.
It was pretty much just sadism with a thin veneer of justification to buy them the small amount of legitimacy they needed to operate within their fascist governments.
There's a clear cause: