Actually dhoti, kurta and chadar are known all over India, even Muslims wear this kind of dress. According to the Varna and Ashrama there is dress. The renuniciates sannyasi and brahmacaris wear only unsown cloth – two pieces, to cover the upper and lower region of the body, sometimes only one peace to cover the lower part. For deity worship this is also a standard. There is also babaji-vesha what some vaishnavas wear. Especially at Radhakunda and places like that. For preaching one can use whatever helps. The main thing is a Vaishnava is always clean inside and outside. And is dressed with vaishanva qualities
titikshavah karunikah, suhrdah sarva-dehinam
ajata-satravah shantah, sadhavah sadhu-bhushanah
The symptoms of a sadhu (Vaishnava) are that he is tolerant, merciful and friendly to all living entities. He has no enemies, he is peaceful, he abides by the scriptures, and all his characteristics are sublime. (SB 3.25.21)
Karmis change their professions at any moment, but a Krishna conscious person does not change his profession, for his only profession is to attract the attention of Krishna by chanting the Hare Krishna mantra and living a very simple life, without following daily changes of fashion. In our Krishna consciousness movement, fashionable persons are taught to adopt one fashion - the dress of a Vaishnava with a shaved head and tilaka. They are taught to be always clean in mind, dress and eating in order to be fixed in Krishna consciousness. What is the use of changing one's dress, sometimes wearing long hair and a long beard and sometimes dressing otherwise? This is not good. One should not waste his time in such frivolous activities. One should always be fixed in Krishna consciousness and take the cure of devotional service with firm determination. (SB 6.5.14)
If a person only externally dresses like a Vaishnava and uses vaishnava-symbols like tilaka, neckbeads, shaven head or Brahmin thread, but doesn’t behave like a Vaishnava then he or she is actually not a Vaishnava.
Unfortunately, in this Age of Kali there are many mundane persons in the dress of Vaishnava, and Srila Bhaktivinoda Thakura has described them as disciples of Kali. He says kali-cela. He indicates that there is another Vaishnava, a pseudo Vaishnava with tilaka on his nose and kanthi beads around his neck. Such a pseudo Vaishnava associates with money and women and is jealous of successful Vaishnava. Although passing for a Vaishnava, his only business is earning money in the dress of a Vaishnava. Bhaktivinoda Thakur therefore says that such a pseudo Vaishnava is not a Vaishnava at all but a disciple of Kali-yuga. (CC Madhya 1.220)
Even Brahman thread and shaven head is a Vaishnava tradition – its varnashrama. Srila Bhaktisiddhanta Sarasvati introduced daivi-varnashram, so that the devotees would also wear the symbols of sannyasa, grihstha and brahmacari and act accrdendly. Actually many Grihasthas at Lord Caitanyas time and also later had longer hair. But Prabhupada introduced a movement and culture; therefore he demanded that everyone should shave. He called long hairs – hippie seeds.
Hiranyakashipu advised his assistants: “My dear demons, give complete protection to this boy at the guru-kula where he is instructed, so that his intelligence will not be further influenced by Vaishnava who may go there in disguise.”
In our Krishna consciousness movement, the tactic of dressing oneself like an ordinary karmi is necessary because everyone in the demoniac kingdom is against the Vaishnava teachings. Krishna consciousness is not at all to the liking of the demons of the present age. As soon as they see a Vaishnava dressed in saffron garments with beads on his neck and tilaka on his forehead, they are immediately irritated. They criticize the Vaishnava by sarcastically saying Hare Krishna, and some people also chant Hare Krishna sincerely. In either case, since Hare Krishna is absolute, whether one chants it jokingly or sincerely, it will have its effect. The Vaishnava is pleased when the demons chant Hare Krsna because this shows that the Hare Krishna movement is taking ground. The greater demons, like Hiranyakashipu, are always prepared to chastise the Vaishnava, and they try to make arrangements so that Vaishnava will not come to sell their books and preach Krishna consciousness. Thus what was done by Hiranyakashipu long, long ago is still being done. That is the way of materialistic life. Demons or materialists do not at all like the advancement of Krishna consciousness, and they try to hinder it in many ways. Yet the preachers of Krishna consciousness must go forward -- in their Vaishnava dress or any other dress -- for the purpose of preaching. Canakya Pandita says that if an honest person deals with a great cheater, it is necessary for him to become a cheater also, not for the purpose of cheating but to make his preaching successful. (SB 7.5.7)
A peaceful, equipoised person who is factually advanced in spiritual consciousness does not need to accept the symbols of a sannyasi, such as the tridanda and kamandalu. According to necessity, he may sometimes accept those symbols and sometimes reject them.
There are four stages of the renounced order of life - kuticaka, bahudaka, parivrajakacarya and paramahamsa. Herein, Srimad-Bhagavatam considers the paramahamsas among the sannyasis. The Mayavadi impersonalist sannyasis cannot attain the paramahamsa stage. … Unless one is in the paramahamsa stage, he is not eligible to understand the Srimad-Bhagavatam. For paramahamsas, or sannyasis in the Vaishnava order, preaching is the first duty. To preach, such sannyasis may accept the symbols of sannyasa, such as the danda and kamandalu, or sometimes they may not. Generally the Vaishnava sannyasis, being paramahamsas, are automatically called babajis, and they do not carry a kamandalu or danda. Such a sannyasi is free to accept or reject the marks of sannyasa. His only thought is "Where is there an opportunity to spread Krishna consciousness?" Sometimes the Krishna consciousness movement sends its representative sannyasis to foreign countries where the danda and kamandalu are not very much appreciated. We send our preachers in ordinary dress to introduce our books and philosophy. Our only concern is to attract people to Krishna consciousness. We may do this in the dress of sannyasis or in the regular dress of gentlemen. Our only concern is to spread interest in Krishna consciousness. (SB 7.13.9)
sarvabhauma-upadeshe chadi' raja-vesha
ekala vaishnava-veshe karila pravesha
Following Sarvabhauma Bhattacarya's instructions, the King had given up his royal dress. He now entered the garden in the dress of a Vaishnava. (dress of Vaishnava means that he wore the dress of a pujari).
Sometimes members of the International Society for Krishna Consciousness - especially in the Western countries - find it difficult to approach people to distribute books because people are unfamiliar with the traditional saffron robes of the devotees. The devotees have therefore inquired whether they can wear European and American dress before the general public. From the instructions given to King Prataparudra by Sarvabhauma Bhattacarya, we can understand that we may change our dress in any way to facilitate our service. When our members change their dress to meet the public or to introduce our books, they are not breaking the devotional principles. The real principle is to spread the Krishna consciousness movement, and if one has to change into regular Western dress for this purpose, there should be no objection. (CC Madhya 14.5)
Hamsaduta: Someone has said that the dhoti, the dhoti that the brahmacaris wear, is the dress that's worn in Vaikuntha. Is that correct?
Prabhupada: Just see Vishnu. He has no coat-pant. Or Krishna, He has no dress – like that. He is also bare upper body. Only Radharani is covered. In India also, still, the covering of the body is only for woman, but men, this, practically one dhoti is sufficient. (SP Room Conversation - April 11, 1969, New York)
While worshiping the deity, you should not wear the following types of cloth: brightly-colored cloth (for men), damp cloth, cloth that is too long or too short to be worn properly, stitched or sewn cloth (for men), torn cloth, oil or dirt stained cloth, soiled cloth, burnt cloth, or cloth chewed by animals or insects. However, you may wear silk many times before washing it, provided it has not contacted anything impure or been worn in impure places.
Unbleached, raw matka (ahimsa) silk is the best for puja. Sheep’s wool is said to be always pure, but still, you should not wear ordinary woolen cloth when worshiping the deity, because wool particles may fall on the deity’s paraphernalia. However, you may wear wool cloth if it is very fine, “nonshedding” wool, in which case you should reserve these items only for puja. Synthetic cloth should not be worn when worshiping the deity.