Everyone is qualified for bhakti

Srimad Bhagavatam 2.9.36, purport:

The lowest of human beings can be elevated to the highest stage of devotional life if they are trained by the bona fide spiritual master well versed in the transcendental loving service of the Lord. If the lowest can be so elevated, then what to speak of the highest, who are well versed in the Vedic knowledge? The conclusion is that devotional service to the Lord is open for all, regardless of who they are. That is the confirmation of its application for all kinds of performers of the service.

Therefore the devotional service of the Lord with perfect knowledge through the training of a bona fide spiritual master is advised for everyone, even if one happens not to be a human being. This is confirmed in the Garuda Purana as follows:
"Even the worms, birds and beasts are assured of elevation to the highest perfectional life if they are completely surrendered to the transcendental loving service of the Lord, so what to speak of the philosophers amongst the human beings?"
Therefore there is no need to seek properly qualified candidates for discharging devotional service to the Lord. Let them be either well behaved or ill trained, let them be either learned or fools, let them be either grossly attached or in the renounced order of life, let them be liberated souls or desirous of salvation, let them be inexpert in the discharge of devotional service or expert in the same, all of them can be elevated to the supreme position by discharging devotional service under the proper guidance. This is also confirmed in the Bhagavad-gita (9.30, 32) as follows:

api cet su-duräcäro
bhajate mäm ananya-bhäk
sädhur eva sa mantavyaù
samyag vyavasito hi saù
mäà hi pärtha vyapäçritya
ye 'pi syuù päpa-yonayaù
striyo vaiçyäs tathä çüdräs
te 'pi yänti paräà gatim

Even if a person is fully addicted to all sorts of sinful acts, if he happens to be engaged in the loving transcendental service of the Lord under proper guidance, he is to be considered the most perfect holy man without a doubt. And thus any person, whatsoever and whosoever he or she may be—even the fallen woman, the less intelligent laborer, the dull mercantile man, or even a man lower than all these—can attain the highest perfection of life by going back home, back to Godhead, provided he or she takes shelter of the lotus feet of the Lord in all earnestness. This sincere earnestness is the only qualification that can lead one to the highest perfectional stage of life, and unless and until such real earnestness is aroused, there is a difference between cleanliness or uncleanliness, learning or nonlearning, in the material estimation. Fire is always fire, and thus if someone touches the fire, knowingly or unknowingly, the fire will act in its own way without discrimination.