What are the most common film genres made by the worst directors?
d_quality = 5 refers to the best directors, d_quality = 0 refers to the worst directors
SELECT T2.genre FROM directors AS T1 INNER JOIN movies2directors AS T2 ON T1.directorid = T2.directorid WHERE T1.d_quality = 0 GROUP BY T2.genre ORDER BY COUNT(T2.movieid) DESC LIMIT 1