That salesman is such a hound dog, showing up at my door every day.

hound dog 由 hound（猎犬）和 dog（狗）组成，hound 特指用于追踪猎物的犬类，以执着和耐力著称。 hound dog 在俚语中常用来形容"死缠烂打的人"，就像猎犬追踪猎物一样紧追不舍。