Instances of Alien Warriors spitting acid?

[The Alien Predator]

Yeah - the Runner spits in AvP 2010. Completely forgot about that.

The Praetorians did too.

Did they? I never had this happen to me during my playthroughs.

Unless you meant in other media?

It wouldn't surprise me if Praetorians could spit acid.

[Born Of Cold Light]

He showed no signs of paralysis, at all. I've speculated that it might have been laced with some kind of mind-controlling chemical substance: Acid melts through the skin and allows it fast entry to the prey's system, whereupon it causes them to be suicidal.

But that doesn't account for why none of the other characters seem to notice how bizarre his behaviour is.

It could have been a numbing chemical.  As to why the other characters didn't react to his changed behavior, I think that the situation was so tense that they didn't think to reflect.  Although, remember that Vriess didn't understand what was going on and begged Christie not to cut himself loose. 

[Corporal Hicks]

He showed no signs of paralysis, at all. I've speculated that it might have been laced with some kind of mind-controlling chemical substance: Acid melts through the skin and allows it fast entry to the prey's system, whereupon it causes them to be suicidal.

But that doesn't account for why none of the other characters seem to notice how bizarre his behaviour is.

It took his apparent lose of strength to be signs of paralysis or some sort of sedative. That'd make more sense.

[HuDaFuK]

Did they? I never had this happen to me during my playthroughs.

Yep. They spit two giant blobs of acid as opposed to the single smaller one the Runners hurled.

It was quite rare though, they would only do it against the Predator when you jump to a platform the Praetorian can't reach. In the Marine campaign you can never go anywhere the Praetorians can't get, so they never used the ranged attack.

[predxeno]

In Aliens vs. Predator: Extinction, drones can spit acid, in Aliens vs. Predator (2010) Jungle Aliens/Runners and Praetorians morphed from them can spit acid, and in Aliens: Extermination, Queens can spray gushes of acid.

[PsyKore]

There's usually always some that spit in every game. However, Konami's Aliens arcade game was probably the first instance I saw of them spitting. That was back in 1990.

[Corporal Hicks]

I think that game had just about any variation you could think of!