Due to constant engagement in devotional service—hearing, chanting, remembering, worshiping the Deity, etc., as prescribed in nine varieties—there are different symptoms which appear in the body of a devotee. These eight bodily transformations, which indicate that a devotee is already liberated within himself, are called aṣṭa-sāttvika-vikāra (CC-1:14:99). When a devotee completely forgets his bodily existence, he should be understood to be liberated. He is no longer encaged in the body. The example is given that when a coconut becomes completely dry, the coconut pulp within the coconut shell separates from the bondage of the shell and the outer covering. By moving the dry coconut, one can hear that the pulp within is no longer attached to the shell or to the covering. Similarly, when one is fully absorbed in devotional service, he is completely disconnected from the two material coverings, the subtle and gross bodies. Dhruva Mahārāja actually attained this stage of life by constantly discharging devotional service. He has already been described as a mahā-bhāgavata, for unless one becomes a mahā-bhāgavata, or a first-class pure devotee, these symptoms are not visible. Lord Caitanya exhibited all these symptoms. Ṭhākura Haridāsa also exhibited them, and there are many pure devotees who manifested such bodily symptoms. They are not to be imitated, but when one is actually advanced, these symptoms are exhibited. At that time it is to be understood that a devotee is materially free. Of course, from the beginning of devotional service the path of liberation immediately opens, just as the coconut taken from the tree immediately begins to dry; it simply takes some time for the shell and pulp to separate from one another.
(Srimad Bhagavatam-4:12:18--purport).

My dear Vyāsa, even though a devotee of Lord Kṛṣṇa sometimes falls down somehow or other, he certainly does not undergo material existence like others (fruitive workers, etc.) because a person who has once relished the taste of the lotus feet of the Lord can do nothing but remember that ecstasy again and again.

A devotee of the Lord automatically becomes uninterested in the enchantment of material existence because he is rasa-graha, or one who has tasted the sweetness of the lotus feet of Lord Kṛṣṇa. There are certainly many instances where devotees of the Lord have fallen down due to uncongenial association, just like fruitive workers, who are always prone to degradation. But even though he falls down, a devotee is never to be considered the same as a fallen karmī. A karmī suffers the result of his own fruitive reactions, whereas a devotee is reformed by chastisement directed by the Lord Himself. The sufferings of an orphan and the sufferings of a beloved child of a king are not one and the same. An orphan is really poor because he has no one to take care of him, but a beloved son of a rich man, although he appears to be on the same level as the orphan, is always under the vigilance of his capable father. A devotee of the Lord, due to wrong association, sometimes imitates the fruitive workers. The fruitive workers want to lord it over the material world. Similarly, a neophyte devotee foolishly thinks of accumulating some material power in exchange for devotional service. Such foolish devotees are sometimes put into difficulty by the Lord Himself. As a special favor, He may remove all material paraphernalia. By such action, the bewildered devotee is forsaken by all friends and relatives, and so he comes to his senses again by the mercy of the Lord and is set right to execute his devotional service.

In the Bhagavad-gītā it is also said that such fallen devotees are given a chance to take birth in a family of highly qualified brāhmaṇas or in a rich mercantile family. A devotee in such a position is not as fortunate as one who is chastised by the Lord and put into a position seemingly of helplessness. The devotee who becomes helpless by the will of the Lord is more fortunate than those who are born in good families. The fallen devotees born in a good family may forget the lotus feet of the Lord because they are less fortunate, but the devotee who is put into a forlorn condition is more fortunate because he swiftly returns to the lotus feet of the Lord, thinking himself helpless all around.

Pure devotional service is so spiritually relishable that a devotee becomes automatically uninterested in material enjoyment. That is the sign of perfection in progressive devotional service. A pure devotee continuously remembers the lotus feet of Lord Śrī Kṛṣṇa and does not forget Him even for a moment, not even in exchange for all the opulence of the three worlds. (Srimad Bhagavatam--1:5:19--translation and purport).