What is hidden shirk? How can it affect subconscious mind?

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.

The Prophet clarified very well what hidden Shirk means, and he explained that it is showing off. An example is when a man prays and he prolongs his prayer when he notices that other people are watching him.

Abu Sa’eed narrated that the Prophet said: “Shall I not tell you about that which I fear more for you than the Dajjaal?" We said: "Yes." He said: "Hidden Shirk; which is when a man stands to pray and makes it look good because he sees a man looking at him.” [Ahmad and Ibn Maajah. Al-Haakim classified it as authentic and Ath-Thahabi agreed with him]

Hence, one should make sure his intention and motive to act are sincere, as he might act to show off without feeling it.

As regards the second part other of your question, then we did not clearly understand what you mean by it.

Allah knows best.