All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Whatever Allah, The Exalted, informed about is undoubtedly true, and it is incumbent on a believer to believe in it and not subject it to such delusions. The fact that some disbelievers do not show the signs you mentioned (at the time of death) does not entail that they would not be tortured and reprimanded by the angels or that they [the angels] would not strike their faces and their backs (as stated in the relevant verse). This belongs to matters of the Unseen, of which we do not have knowledge, and the knowledge of such matters is only established through authentic Divine revelation.
Allah Knows best.