Tā nà tào shuōcí lǚshì-bùshuǎng, zǒng néng ràng rén xìnfú.
His line of argument never fails to convince people.
Tips
usage
爽 here means 'error' or 'deviation' (an archaic sense), NOT comfortable. So 不爽 = no deviation, i.e. it works without fail. Contrast with the modern colloquial 不爽 meaning 'unhappy'.
