Buying them in a dream is disliked in interpretation, because rags are poverty; selling them is good, because he wards off something disliked from himself. The seller of old clothes is a man of moderate means. Buying old clothes signifies poverty, and selling them is the end of poverty.
Dream meaning · al-Nabulsi
Old worn-out clothes خلقان الثياب في المنام
Source: al-Nabulsi, Ta'tir al-Anam fi Ta'bir al-Manam, p. 104. English translation by iDreamBot. Quran verses: Quran.com, Saheeh International.