If we but turn our gaze to the high qualifications of the members of Bahá’í Assemblies … we are filled with feelings of unworthiness and dismay, and would feel truly disheartened but for the comforting thought that if we rise to play nobly our part every deficiency in our lives will be more than compensated by the all-conquering spirit of His grace and power. Hence it is incumbent upon the chosen delegates to consider without the least trace of passion and prejudice, and irrespective of any material consideration, the names of only those who can best combine the necessary qualities of unquestioned loyalty, of selfless devotion, of a well-trained mind, of recognized ability and mature experience.…
(From a letter dated 3 June 1925 written by Shoghi Effendi to the delegates and visitors at the convention of the United States and Canada, published in Bahá’í Administration: Selected Messages 1922–1932, p. 88) 
With reference to your next question concerning the qualifications of the members of the Spiritual Assembly: there is a distinction of fundamental importance which should be always remembered in this connection, and this is between the Spiritual Assembly as an institution, and the persons who compose it. These are by no means supposed to be perfect, nor can they be considered as being inherently superior to the rest of their fellow-believers. It is precisely because they are subject to the same human limitations that characterize the other members of the community that they have to be elected every year. The existence of elections is a sufficient indication that Assembly members, though forming part of an institution that is divine and perfect, are nevertheless themselves imperfect. But this does not necessarily imply that their judgement is defective. For as ‘Abdu’l-Bahá has repeatedly emphasized Bahá’í Assemblies are under the guidance and protection of God. The elections, especially when annual, give the community a good opportunity to remedy any defect or imperfection from which the Assembly may suffer as a result of the actions of its members. Thus a safe method has been established whereby the quality of membership in Bahá’í Assemblies can be continually raised and improved. But, as already stated, the institution of the Spiritual Assembly should under no circumstances be identified with, or be estimated merely through, the personal qualifications of the members that compose it.
…I feel that reference to personalities before the election would give rise to misunderstanding and differences. What the friends should do is to get thoroughly acquainted with one another, to exchange views, to mix freely and discuss among themselves the requirements and qualifications for such a membership without reference or application, however indirect, to particular individuals. We should refrain from influencing the opinion of others, of canvassing for any particular individual, but should stress the necessity of getting fully acquainted with the qualifications of membership referred to in our Beloved’s Tablets and of learning more about one another through direct, personal experience rather than through the reports and opinions of our friends.
These local Spiritual Assemblies will have to be elected directly by the friends, and every declared believer of 21 years and above, far from standing aloof and assuming an indifferent or independent attitude, should regard it his sacred duty to take part, conscientiously and diligently, in the election, the consolidation, and the efficient working of his own local Assembly.
(From a letter dated 12 March 1923 written by Shoghi Effendi to the Bahá’ís of America, Australasia, France, Germany, British Isles, Italy, Japan, and Switzerland, published in Bahá’í Administration: Selected Messages 1922–1932, p. 39) 
…the elector … is called upon to vote for none but those whom prayer and reflection have inspired him to uphold. …the practice of nomination, so detrimental to the atmosphere of a silent and prayerful election, is viewed with mistrust inasmuch as it gives the right to the majority of a body that, in itself, under the present circumstances, often constitutes a minority of all the elected delegates, to deny that God-given right of every elector to vote only in favour of those whom he is conscientiously convinced are the most worthy candidates.…
(From a letter dated 27 May 1927 written by Shoghi Effendi to the National Spiritual Assembly of the United States and Canada, published in Bahá’í Administration: Selected Messages 1922–1932, p. 136)