One of the relatively younger Bell Labs guys who experienced Hamming (in my memory it was either Ken Thompson or Kernighan) described in a public talk the way Hamming would approach young scientists and engineers in the cafeteria and harangue them if he deemed their current area of research non-world shaking, and therefore unworthy of their attention. It was a hilarious story because Hamming was described after a brief pause as a "curmudgeon" but one got the distinct impression Hamming's younger associates had other, more colorful words to describe him.