Nowadays, we find there are so many devotees getting paid to perform bhajana/kirtan like professional singers, I guess that is nice for them, but real Kirtan is explained by Srila Prabhupada in this 1967 letter to Jadurani dd.
Krishna Kirtan is not for earning livelihood. Krishna Kirtana is not meant for entertaining the public for demonstration of arts. It is dynamic service to the Lord. We do not therefore mind so much about the artistic presentation of Krishna Kirtan but we want to see how much a devotee is satisfying the Supreme Will. (Prabhupada letter to Jadurani 12th December, 1967)
Full letter
Letter to: Jadurani
Calcutta
12 December, 1967
Please accept my blessings. I am in due receipt of your letter Dec. 3, 1967. You have described in your letter that my presence again before you will be wonderful. I quite agree with you. Your sincere prayer to Lord Nrsimhadeva is helping me to recuperate my health., and you will be glad to know that I am arriving at San Francisco on 14 Dec. at 12:45 pm by PAA 846. I can understand that you are all thinking of me 24 hrs and therefore Satsvarupa had a dream that I had gone to Boston and was enjoying your company. Similarly, I also think of you all, especially of you because you are so nice and good. I understand also, there was a Kirtan performance given by Sri Purna das. You have rightly remarked whether they are devotees. You are right. These people are professional singers. Krishna Kirtan is not for earning livelihood. Krishna Kirtana is not meant for entertaining the public for demonstration of arts. It is dynamic service to the Lord. We do not therefore mind so much about the artistic presentation of Krishna Kirtan but we want to see how much a devotee is satisfying the Supreme Will. The pictures of Lord Krishna and His expansions are particularly meant for giving chance to the neophytes for offering devotional service. It was very nice that Purna das offered respects to the Sankirtan painting. That will enlarge Krishna Consciousness. Your program for publishing pictures in details of great authorities like Bhisma and others is very much appreciated. I am so glad to learn that Rayarama, Satsvarupa, yourself, Gaurasundara, Govindarani and others are doing so much for improving BTG. I quite appreciate your endeavours and you must continue the Majajana series, and whenever necessary you can ask me for necessary informations. I would advise, unless there is dire necessity, you should not divert your attention from painting. Somehow or other you have to manage everything in full cooperation, but your main engagement is painting. Your God-brothers, Acyutananda and Ramanuja das are doing well here. We very much appreciate your offering of respects and they wish to convey the same to you. Hope you are well.
Your ever well-wisher
A.C. Bhaktivedanta, Swami
The Hare Krishna Movement 