grubbiest
grub-bi-est
adjective
The superlative form of 'grubby', meaning most dirty, unkempt, or squalid.
"That old pub was the grubbiest place I'd ever seen."
Thesaurus
Synonyms: grubby, grimy, raunchy, dirty, unclean, grungy, dingy, soiled, begrimed, Myxocephalus aenaeus