Maulana Manzoor Nomani Rahimullah writes

(excerpts Translated from urdu book available here)

"I have always been of opinion that this name TABLEEGH and those who are
working in it as TABLIGHI JAMAAT is creating many confusion for many
people. It cause many misconceptions. From the word TABLEEGH people
think that it is a work of Preaching (Nassehat o Waaz) and TABLIGHI
JAMAAT is a tem or Party of these Preachers.
That’s why they expect that they should have an upper level of knowledge
required for Preaching /WAAZ/Naseehat. And practically in action (AMALI)
they also expect that they should not have a visiblt shortcoming.1.In this
background when they see someone in Tablighi Jamaat not even knowing
Wazu Properly or their appearance is not according to shariah they become
extremely critical. They further become surprised after seeing them that
they are insisting on others to spare some time from their busy schedule and
to go in the path of Allah for near and far as they think that
If preaching Waaz and Naseehat has to be done then why not in our locality
instead of going far away.
Bhar Hall
All these confusion comes from basic wrong concept of considering
Preaching/Waaz Naseehat as the work of Tablighi Jamaat.
Actually here the name TABLEEGHI JAMAAT means
“Here TABLEEGHI JAMAAT means a system of developing a deeni and
Dawat Environment in with a person will be with certain Usools will do the
Aamal of Dawat Taleem o Taallum (teaching and learning) Ibadat and
Khidmat (Service) .
With this environment it is expected to have an increase in
1. attachment to Islam,
2.increase in Emaan,(Belive in Allah and Rasool command and words),
3. reformation of Action
4.seeking of knowledge and
5.Islah e Nafs
6.Development of Jazba of sacrifice for Islam.
That’s why all muslims with whatever lag in his knowledge or action (Ilm o
Amal ki Kmee) is not only invited rather sometimes pulled and no minimum
condition is put as eligibility for going in TABLIGHI JAMAAT.it is expected that
with this Environment he will take good effect and Allah the actual caller and
the master of our heart will bless him with hidayat.
And that’s why in TABLIGHI JAMAAT all kind of and all strata of people are
there.
However as you have written it is correct that sometimes in small public
gatherings some people starts addressing who are actually not eligible at all
for address. And they even don’t know the work of Tablighi Jamaat. They
donot remain in the boundary of their knowledge in talk.
But as you are considering it as bad the Zimmedar brothers (Responsible
Brothers)also consider it as bad and wants to correct it. They give instruction
to Jamaat before its departure about the talk and if all the guidance is
followed these mistakes will not happen. But the thing is these mistakes are
not rare and this matter is really important for the Responsible Brother. My
personal opinion is that apart from Advice if some written instruction is also
given these things may be corrected to a greater extant........."

English translation is available here