Imam al-Shafi'i (may Allah have mercy on him) said that a relative of Sayyiduna Uthman (may Allah be pleased with him) came to him, and he asked him about his livelihood. He mentioned a bathhouse or a cupper, or he mentioned two cuppers, and he said: Your earnings are filth, or he said 'danas' (dirty) or 'dani' (lowly), or mentioned another word like it. "The earnings of the cupper are dirty."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19521