So ebony and wenge are tone killers?
Those are two different things.
No disrespect to the builders but being a luthier does not give anyone special hearing abilities. It's so easy to demonstrate the fact that our beliefs in what something will sound like will have a major influence on what we decide it sounds like that no amount of saying you hear something while knowing what the wood is before hearing it, has any scientific value. It does however have great marketing value which is actually a strike against a builders opinion for testing purposes. The fact they will so often contradict each other also shows a flaw in this assumption.
The only way to tell if we can really hear the difference is to be able to detect the difference without looking at the answer first. Looking at the bass first and then listening is simply asking ourselves if we're as smart as we think we are. Answer yes or no. We usually pick yes