This is the 12759th most frequent Polish word.
nieuczciwego
Dishonest.
Here, 'nieuczciwego' is used as an adjective in the accusative case, modifying the noun 'sprzedawcę' which is also in the accusative case as the direct object of the verb 'złapano.'
Nieuczciwego sprzedawcę złapano na oszustwie.
The dishonest seller was caught cheating.
In this sentence, 'nieuczciwego' functions as an adjective in the genitive case to modify 'traktowania,' which is in the genitive case and is the object of the negated verb 'lubią.'
Ludzie nie lubią nieuczciwego traktowania.
People do not like unfair treatment.
Here, 'nieuczciwego' serves as an adjective in the genitive case, describing 'postępowania,' which is in the genitive case as the object of the verb 'nigdy nie wybaczyła.'