Demai, Chapter Three, Mishnah One
This mishnah discusses various people to whom one might legitimately give demai. As we have seen already, since treating the produce of an am haaretz as demai, that is doubting whether it was tithed, was only a rabbinic stringency, the rabbis allowed the law to be lenient in certain circumstances.
1) They may feed demai to the poor and to guests (alt. passing troops).
a) Rabban Gamaliel used to feed demai to his workmen.
2) [As for] charity collectors:
a) Bet Shammai says: they should give tithed [produce] to one who doesnt tithe, and untithed [produce] to one who does tithe. In this way it will turn out that every one will eat [produce] that has been fixed (tithed).
b) But the sages say: they may collect indiscriminately and distribute indiscriminately. And one who wishes to fix [his produce by tithing it], let him fix it.
Section one: Since the rules of demai are only stringencies, for as we have said deoraita, from Torah law, one can eat demai without tithing it, there are certain leniencies. One is that a person may use demai to feed the poor and to feed his guests. It is a mitzvah to feed both the poor and to treat guests hospitably and hence one can use demai. Others explain that the Hebrew word which I have translated and explained as for guests actually mean passing troops, who are treated like the poor because they have no home to call their own.
Rabban Gamaliel would even feed demai to his workers, probably because there is a mitzvah for an employer to feed his workers.
Section two: According to Bet Shammai, when charity collectors collect produce to give to the poor, they should separate the tithed produce from the untithed produce and give the tithed produce to those who wont tithe it, and the untithed produce to those who will. In other words, the charity collector has a responsibility to make sure that those receiving the charity observe the laws of tithing.
Bet Hillel, on the other hand, gives greater trust and freedom to people. Charity collectors can collect either tithed or untithed produce and then it will be up to the person buying it to decide whether to tithe or not. Perhaps we might even say that there is something beneficial about leaving the choice to tithe in the hands of the purchaser. By choosing to tithe he is making a more active choice as to his religious observance, as opposed to Bet Shammais system, in which a person has to tithe (or at least his produce will end up being tithed) without having any choice in the matter.