Where there's muck there's brass
Possible interpretation: There is money to be made in dirt and dirty jobs. For example, many people have made fortunes by processing rubbish or waste materials.Note: muck (noun) = dirt; rubbish | brass (noun) = a metal made from copper and zinc; (British slang) money
Origin: This specific saying originated in Yorkshire, England in the 20th century. The slang term "brass" (for "money") was and is typically used in Yorkshire. In the 19th-century, people said: "Where there's muck there's money." And the 17th-century book "A collection of English proverbs" (Rev. John Ray) includes a similar idea: "Muck and money go together."