QuoteIn theory, yes, but on screen, I would argue that the movies all respected this piece of lore that was established in the original film. That is, which of the 4 Alien movies had a scene where the acid blood was anything less than acidic? AvPR in particular had a few scenes where the Alien blood had no effect on the area where it landed (presumably, we can't see every detail, darkness notwithstanding).
There's a bunch of scenes where the Alien acid is incredibly potent, arguably moreso than in any other movie in the series. The only scene in AvPR I can think of where the acid didn't have an apparent effect was when the Predalien spit up acid after Wolf yanked its inner jaw out at the very end, but I wrote that off as artistic license/Wolf being seconds away from dying and not giving a shit.
Meanwhile in 'Aliens' we see that Alien acid can go through multiple floors of metal grating ("Looks like someone bagged one of Ripley's bad guys") and melt Drake's face off in seconds, but when Hicks blows one's head off with a shotgun and gets acid on Hudson's arm it's hardly even debilitating for him, and later in the movie Hicks takes a face (and chest) full of acid in the elevator and he survives it. Likewise, who knows what circumstances caused the acid-hole through multiple floors, but it evidently wasn't explosives and gunfire because we see that happen all over the place in the Ops battle with no acid damage to anyone or anything we can see.
In 'Alien' 1 drop of facehugger blood is enough to go through several decks, but when the Alien takes a speargun shot to the stomach, the acid has no effect.
Although in its defense I'm more than willing to accept that facehugger blood is more potent than adult Alien blood (it even follows a real-world trend where the "venom" of adolescent animals is more potent than that of adults, as a defense mechanism), and that at that point in the series the creators may not have intended for the adult Alien to have acid blood like the facehugger did.
In 'Alien3', the Alien spits acid in Murphy's face and completely ruins his shit, but at the end of the movie when the thing
literally explodes, there's no visible effect of the acid on anything at all.
In 'Alien Resurrection', an Alien bleeding goes through multiple decks (and sets the others loose), but when Ripley puts a gun in one's mouth and blows its head off, there's no apparent effect of the acid on anything (nor is there when Johner makes one's head explode on the ladder).
My point is the acid's effect has always been inconsistent, in every movie.