Hare Krishna - Krishna Katha - Chanting with Purity - please find attached document - a must read for all

Real kirtana
Actual krsna-kirtana is that kirtana by which Krsna is pleased. The show of performing kirtana
for one's own pleasure or the pleasure of others is not krsna-kirtana but maya-kirtana.
 As actions are judged by their results, so one can judge whether one is chanting the
holy name by the results. If while chanting Hari's name one's propensity or
attachment for material life increases, one can know that Hari is not the object of one's chanting.
 Hari-nama-sankirtana should destroy attachment for material life, not increase it. While chanting
one will realize the insignificance and temporality of material life, and will no longer relish it.
Then all one's anarthas will be destroyed, one's heart will be purified and become steady,
 one's material restlessness and misery will be destroyed, and one will attain love of God.

(Srila Prabhupada Bhaktisiddhanta Thakura's Amrta Vani)

Chanting with purity
 
Harinam-sankirtan means to loudly chant the holy name for the benefit of others.
We should seriously consider to what extent we are benefiting others, and also to what extent we are
benefiting ourselves. There is apparent kirtan and real kirtan. Only sankirtan where the pure name is
chanted is real sankirtan. If someone is making offenses to the name, simply articulating the syllables
"Hare Krishna," that is not real sankirtan. One must thus carefully consider the offenses to be
avoided in the matter of chanting.
 
Can you talk about the different types of chanting?
 
There is bhukti-nama, offensive chanting, which results in material gain; there is mukti-nama,
shadow chanting, which results in liberation, and there is prema-nama, pure chanting, which results in prema-bhakti, pure love of Godhead.
 
Bhukti-nama means offensive chanting. By chanting offensively, you can benefit others only by
increasing their material piety. Bhaktivinoda Thakura therefore states that a pure devotee
should not participate in kirtan led by offenders to the holy name. Who are those offenders?
Those who do kirtan for ulterior motives–who chant for money, or to augment their sex appeal,
or do it for name and fame. Such chanting can at best result in material gratification.

There is a very nice - must read article - attached document with this mail

written by HH Dhanurdhara Swami maharaja and the interview of HG Aindra Prabhu.