It depends what the opinion is about. The National Socialists boosted Germany's economy massively, so a discussion of their economic policy might be useful (this is a simplification, in actuality the economics of post-WW1 Germany was boosted by a multitude of factors and the Nazis were not the only major one, but my point stands -- they legitimately did a lot of good to Germany before WW2). A discussion of their opinions on racial purity is definitely not going to be useful to anyone involved.
If you found out that the barista at your favourite coffee shop was racist, would that change whether they make good coffee? Is the value of the coffee inextricably linked to their views? If someone has a disgusting view in one aspect of their life, their other views appear to be tainted even if they are entirely orthogonal.
If you found out that the barista at your favourite coffee shop was racist, would that change whether they make good coffee? Is the value of the coffee inextricably linked to their views? If someone has a disgusting view in one aspect of their life, their other views appear to be tainted even if they are entirely orthogonal.