The definition of irony: incongruity between what is expected to be and what actually is, or a situation or result showing such incongruity
So, when I hear the world "experimental," I immediately jump to what usually constitues as "experimental." If I had no previous conceptions about PoS and someone said they just released their most "experimental" album yet, I'd think it would sound spacey, prog rocky, Pink Floyd/Radioheadish, but no...it is "experimental" because it is more forward and less proggy. My expectations are different than reality, thus, irony.