Hey! For those of you on the "nice people are boring" side of the great debate, maybe it's just that the person isn't relevant to you. They're plenty friendly, but you don't think you have anything in common, or they don't have anything to offer you. It's a little ego-centric to call these friendly-but-not-yet-relevant people "boring." In the networking circles that most of us inhabit, you have something in common with just about everyone you meet.
The World's Worst Survivor Contestant (refer back to the Great Debate) probably sizes people up pretty quickly to see if they are first, like her, and second, have anything to offer her and then discards them as "uninteresting" when they don't. It's telling that the few people she did like included Randy, who was the grouchiest man in Survivor Gabon.
Remember this quote from Bilbo Baggins about getting to know people until you like them:
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."