A devotee should be simple and clean dressed, but more than dress, the mind should be clean.
Krishna and pure devotees see through the substance, not the maya the world sees through.
If an ordinary man does not eat, he will grow weak and die. Similarly, if a devotee does not taste the transcendental pastimes of Lord Chaitanya Mahaprabhu and Lord Krishna, he will gradually weaken and die spiritually.
It is the aspiration of a devotee that while he chants the Hare Krsna maha-mantra his eyes will fill with tears, his voice falter and his heart throb. These are good signs in chanting the holy name of the Lord.
Purport on Chaitanya Caritamrta Adi Lila 7.81
Everything that can be achieved by fruitive activities, penance, knowledge, detachment, mystic yoga, charity, religious duties and all other means of perfecting life is easily achieved by My devotee through loving service unto Me. If somehow or other My devotee desires promotion to heaven, liberation, or residence in My abode, he easily achieves such benedictions.