Speaking to Official Xbox Magazine, Valve's Chet Faliszek said the Left 4 Dead 2 team came up with a since-discarded special infected called "The Leaker." He was axed not for doing something disgusting, but predictable.
"With The Leaker, the idea was a kind of Boomer that could take damage, and shoot out spouts of goo. And you could plant yourself and explode - be this walking bomb," Faliszek told OXM. "The problem is there's a warning that you're going to do that. So when you go to plant yourself, everyone else runs away, and you just die and don't hurt anybody."
So they scotched The Leaker, but carried over some of his properties to The Spitter, Faliszek said. Oh, and about that inspired name (and others)? It's "because I'm lazy," Faliszek said. "'What does this one do?' 'It charges.' 'Yeah, it's a Charger. I'll go with that.'"
Interview with Valve's Chet Faliszek [Official Xbox Magazine]