I have :) I am Tamil brahmin Iyer myself and I've spent quite a bit of time at the "agraharams". There are some brahmins who are extremely orthodox. They won't eat anything that grows under the ground, share utensils or even physically touch anyone they perceive to be a meat eater. This is however something that you usually observe with people living in temple adjacent communities or in very rural areas with religious duties. The rest are fairly urbanized so you don't see this normally.

I was just trying to give the benefit of the doubt to the family you ate with. But I now know whats going on here.