echar a perder

(v.) = ruin, bungle, bring out + the worst in
Ex: Besides, winding up in an exclusive arrangement with a distributor that has rotten customer service ruins any advantage. Ex: Regrettably, the well-intentioned publication of Devereux's typescript has been incurably bungled, and Rastell remains without either a complete or trustworthy bibliography. Ex: Although there are some bad stepparents in the real world, becoming a stepmother or stepfather does not inevitably bring out the worst in people.