probably at a petting zoo.
llamas in petting zoos were raised being pet by people, usually since they were very young babies. This makes them treat people how they would usually treat other llamas, like spitting on them. but the behavior can get out of hand, and even lead to Berserk Male Syndrome.
llamas raised properly will not spit on a person unless extremely stressed. only on each other.
i have never been spat at on purpose by a llama. and i have been raising them for about 9 years.