Here’s a letter by Srila Prabhupada, dated June 14, 1972, to his disciple Himavati Devi Dasi explaining that devotees should dress nicely.
My Dear Himavati,
Please accept my blessings. I beg to acknowledge receipt of your letter dated May 30, 1972, and I have noted the contents. I don’t know who has given you this idea of shaving your head and wearing white garments. In India only the widows are allowed to shave head. I have never suggested your husband to take to Sannyas, but we can discuss this matter further when we shall meet again in London for Rathayatra.
You remain the beautiful maid servant of Krishna. That is your business, and you should dress yourself always very nicely so that Krishna by seeing you will be pleased. Don’t try to be ugly before Krishna. Krishna does not like ugly gopis. We are transcendental artists, musicians, writers, so everything should be beautiful for Krishna. After all we are members of Krishna’s family, just like Krishna had 16,000 wives and each wife has thousands of servants and maid-servants and all of them are very beautiful for serving Krishna and His Queens. So the servants of the gopis and queens cannot be ugly, they are as beautiful as the queens. In the Vaikuntha world there is no need of serving anything because everything is already clean and beautiful. It is so clean that just like a mirror when the maid-servants would sweep the floor they could see the reflections of their bodies. So remain always compact in Vaikuntha yagna, simply by thinking of the Glories of the Lord. Don’t try to do anything artificially. That is sahajia, which means a class of men that take everything very cheap. You want to perform sacrifice so continuously read our Vedic scriptures and perform the Vaikuntha yagna.
Hoping this will meet you and your good husband in the best of health,
Your ever well-wisher,
A.C. Bhaktivedanta Swami