Oh, what a lovely question! The comparative form of "dirty" is "dirtier," and the superlative form is "dirtiest." Just like in nature, even the dirtiest of things can be transformed into something beautiful with a little love and care.
Superlative and comparative of dirty
dirtier, dirtiest
The comparative is greater and the superlative is greatest.
Comparative - better Superlative - best
comparative straighter and the superlative the straightest
Superlative and comparative of dirty
dirtier, dirtiest
Dirtier and dirtiest
dirtier, dirtiest
dirtier, dirtiest
dirtier, dirtiest
Dirtier and dirtiest.
comparative : purer superlative : purest
Comparative: older Superlative: oldest
Dative; Early Comparative; Earlier Superlative; Earliest
The comparative and superlativeforms of grand are: Comparative: grander Superlative: grandest
comparative - merrier superlative - merriest