[paulz_]

I can see what your getting at but I think this applies beyond programming languages. If you're interviewing someone who is into a niche programming language it can be a sign they are more interested in programming than say, someone who only knows Java etc. Obviously this won't always be the case and can lead to a weird sort of credentialing where people pretend to be into obscure languages.

It would be like if you were interviewing a chef who was saying "yeah yeah pan frying is fine but let me tell you about sous vide."

Then you go on to interview another guy who is into working the grill at chain restaurants.

Is the Sous Vide guy better? Certainly not always. But it can be an indicator this guy is a real nerd about cooking in a way that results in a better meal at the end.

[sdfsfsf3kjdf]

Sure, it's definitely something worth taking into consideration, I just wouldn't value it too highly and in many cases I think there are much better indicators of ability.