Would anyone know how a sealed batch of aspirin dissolves upon putting the tablet into your mouth, while having a gone off sour taste and smelling pungent, similar to a stink bug (http://www.qm.qld.gov.au/Find out a...Bugs/Common species/Stink Bugs or Shield Bugs)?
I found this: http://pharmacopeia.cn/v29240/usp29nf24s0_c1191.html which suggests that in humid conditions aspirin (acetylsalicylic acid, an ester) can hydrolyse to acetic acid (active ingredient in vinegar) plus salicylic acid (o-hydroxybenzoic acid). I can't find anything on what salicylic acid tastes like but it is said to be odourless. So maybe that is not the explanation - unless somehow the plastic packaging is being affected and this is releasing something. Does a tablet fresh from the packet look or smell odd? Is the packaging normal colour and pliability?
I doubt the aspirin is the bad one. The tablet is a package of several compounds. Such as press release agents , fillers , cellulosic compounds, some coating for taste, and others.