not fit to black smb.'s boots

(not fit (или worthy) to black (или to blacken) smb.'s boots)

≈ в подмётки не годится кому-л

I knew some of the men who had written this malevolent twaddle; and I knew they were not worthy to black Lawrence's boots. (R. Aldington, ‘Life for Life's Sake’, ch. 18) — Я знал кое-кого из тех, кто написал эту злобную книжонку. Эти люди не стоят и мизинца Лоренса.