looking for something else alliterative?

Your alliteration argument is compelling, etaoin, but the word "caliginous" can be defended on its own merits when considered in conjunction with the noun which it modifies, namely, "junk" -- which is missing from your quotation.

"Junk" consists of discarded and unused, possibly obsolete, parts and materials, and people typically hide such collections away from view, for instance, in dusty attics or unsightly junkyards.

Junkyards and dusty attics are usually considered "dark, gloomy, obscure" places.

It is no coincidence that "haunted house" amusements have the same abandoned, distressed, creaky, cobwebbed look of a caliginous attic filled with 'junk'.

OZ'S VOICE
"You clinking, clanking, clattering collection of caliginous......junk!"