This article is from the Llamas & Alpacas FAQ, by Michael Shealy and William Bagwell with numerous contributions by others.
Yes, they do spit, but usually at each other. This being over disputes about food primarily. A bred female llama will spit at advances from a male llama. An over-handled llama, improperly socialized without other llamas present, will think humans are llamas and will spit as a normal course of action against the other "llama". A mistreated or mishandled llama, may also spit at humans.
 
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