Question: In male customers with an occupation handlers or cleaners, what is the percentage of customers with a true response?
SQL: SELECT CAST(SUM(CASE WHEN T2.RESPONSE = 'true' THEN 1.0 ELSE 0 END) AS REAL) * 100 / COUNT(T2.REFID) FROM Customers AS T1 INNER JOIN Mailings1_2 AS T2 ON T1.ID = T2.REFID WHERE T1.OCCUPATION = 'Handlers-cleaners' AND T1.SEX = 'Male'