Generally, the right-practising bhikkhu will be a person of few wants for he is trying to go to the ending of all desire.
However, there may be certain things he may need but may not mention until he is sure that the donors are completely sincere in their invitation.
If the donor makes specific suggestions, the bhikkhu may refuse, he may accept, or he may remain silent — and such silence may very well be a positive response (as it was in the Lord Buddha’s time).
Therefore, as the donor gets to know the bhikkhu he or she will become more sensitive about what is needed and what is appropriate — and be able to interpret any “silence” in the right way.
Learn more about the Theravadin Buddhist Monk’s Rules here:
The Bhikkhus’ Rules – Guide for Laypeople