1.Anyone who has made the Srimad Bhagavatam better or more valuable than his own life, those ideal personalities are considered to be mahabhagavata devotees.
(Hari Bhakti Vilasa 10/33 from Skanda Purana)
2. Any devotee of the Supreme Personality of Godhead, after hearing the harsh and dry words from another devotee, tolerates them and pays obeisances to sucha devotee, they are certainly said to be real Vaisnavas.
(Hari Bhakti Vilasa 10/35 from Linga Purana)
3. Anybody, after hearing My transcendental glories becomes jubilant and situates himself in goodness and becomes devoted to that speaker of Krsna'sglories and serves him, such a person is known as abhagavatottama, or highclass devotee.
(Hari Bhakti Vilasa 10/40 from Brhan Naradiya Purana)
4. Anyone whose heart becomes jolly just by hearing the transcendental holy names of Lord Hari with a pleased mind and just by hearing these holy names,his hairs stand on end, he is considered a bhagavata (best devotee).
(Hari Bhakti Vilasa 10/44 from Brhan Naradiya Purana)
5. Engaged constantly in chanting about Me, the Supreme Personality of Godhead, the sadhus do not suffer from material miseries because they are always filledwith thoughts of My pastimes and activities.
(Srimad Bhagavatam 3.25.33)
6. Any person who does not get disturbed by lusty desires and who is always
rigidly attached to the lotus feet of the Supreme Personality of Godhead, heis said to be a Visnu devotee.
(Hari Bhakti Vilasa 10/46 from Visnu Purana - Yamaraja instructs his messengers)
7. Any person who remains attached to Lord Hari within his mind, even if many obstacles come on his path and he does not deviate from his service, it can becertainly understood that he is a devotee of the Supreme Lord.
(Hari Bhakti Vilasa 10/67 from Skanda Purana)
-Srila Sanatana Gosvami gives his Digdarsani-tika commentary on this verse,
Anybody who is really attached to the transcendental subjects of Krsna,he becomes very purified and becomes free from all kinds of personal sense gratification, etc. Any person who wants to hear the transcendental message ofthe Supreme Lord and who wants to chant them with a loud voice and who feels this message is very rarely achieved, one who is attached to the lotus feet of Lord Krsna and one who wants his mind to be tied at His lotus feet, all of these personalities are to be known as Visnu bhaktas or devotees of the Supreme Lord. The sign of a clean devotee is that the devotee's mind is not disturbed. One who is engaged in pure devotional service does not become disturbed in any condition. He sees friends and enemies equally. He naturally develops a desire to not usurp somebody else's property. Everything that he needs is provided by the Supreme Lord, therefore it is said that one whose mind is not disturbed, he is said to be a properly minded person. Thus, he is said to be a Visnu devotee. He does everything. He does his own occupational duty without depending on others. Whatever is possible, he depends on the Supreme Personality of Godhead.
8. Any person whose etiquette is best and proper, who lives according to the scriptures, who is very merciful to all living entities, who is pure and whose actions are offered to the Supreme Lord, are said to be Bhagavata devotees(very advanced devotees).
(Hari Bhakti Vilasa 10/12 from Skanda Purana)
O My mother, O virtuous lady, these are the qualities of great devotees who are free from all attachment. You must seek attachment to such holy men, for this counteracts the pernicious effects of material attachment.
(Bhagavatam 3.25.24 - Lord Kapila to Mother Devahuti)