All Creepy Hollows spirits are bound with cloaking.
Cloaking is a method of providing both the spirit and the vessel an ability to be undetectable by outsiders without the explicit permission of the spirit companion. This provides the spirit, the vessel, and the keeper protection against uninvited attention.
Cloaking takes time to master properly and every experienced conjurer has their own cloaking method. Be cautious of inexperienced practitioners as they usually can’t reliably provide this.