Taharos, Chapter 7, Mishnah 6. Our chapter forms part of a run of mishnayos devoted to the am ha'aretz, the Jew who does not guard himself in matters of taharah, and to the question of how one who does guard himself must deal with such a person and with any place he may have been. Before us are two sorts of uninvited intruders who help themselves into a person's home, and as we will see, the halachah judges each of them by a very different standard.
The tax collectors
"Hagabbaim shenichnesu letoch habayis": if the collectors entered into the house, "habayis tamei," the house is tamei. A word of reassurance to any gabbai who is listening: the mishnah is not speaking about the fellow who collects pledges and hands out aliyos. These gabbaim are tax collectors, men who come on behalf of the government to collect what is owed and to seize something of value as security.
Why is the whole house declared tamei? Because such men are assumed to be amei ha'aretz, and even according to the chachamim, who are generally the lenient voice in these matters, a tax collector does not stand politely at the doorway. He walks through the rooms, looking over everything in sight for an item worth taking for the treasury. Wherever he could have reached, we must assume he reached and touched.
"Im yesh imahen goy": if there is a non-Jew together with them, "ne'emanim lomar lo nichnasnu," they are believed when they say, "We did not go in," and the house remains tahor. Do not let the mention of the non-Jew confuse you. It appears here in order to parallel the closing line of the mishnah, which speaks of thieves accompanied by a non-Jew. The point is that even in the more severe case, where a non-Jew was part of the group, their word that they never entered is accepted, and it goes without saying that their word is accepted when no non-Jew was with them at all.
"Aval einam ne'emanim lomar nichnasnu aval lo naganu": but they are not believed to say, "We did enter, however we did not touch anything." That claim simply does not ring true. Once they have admitted that they were inside, everything in the house must be treated as tamei, since the whole purpose of their visit was to handle whatever they found.
The thieves
"Haganavim shenichnesu letoch habayis, ein tamei ela ad mekom raglei haganavim": when thieves entered the house, nothing is tamei except up to the place that the thieves' feet reached. Here the presumption runs the other way. The tax collector strolls through the house with the confidence of a man who has the government behind him. A thief is frightened of the owner and of being caught, so he does not wander. He takes what is near and he leaves. We therefore restrict the tumah to the areas we know he actually trod, and we do not assume he went any further.
"Umah hen metam'in? Ha'ochlin vehamashkin uchlei cheres hapetuchin": and what do they render tamei? Foods, liquids, and open earthenware vessels. "Aval hamishkavos vehamoshavos uchlei cheres hamukafin tzamid patil, tehorin": but the items used for lying and sitting, and earthenware vessels that are sealed with a tightly fitted covering, remain tahor. The reason is that this thief is a Jew. Even though he is an am ha'aretz, he is not treated as though he has the tumah of a zav, so he does not convey midras tumah to bedding and seats, and he cannot penetrate a sealed earthenware vessel. He conveys tumah only by maga, by direct contact, and therefore only foods, drinks and vessels that were open to his hand are affected.
"Im yesh imahen goy o isha, hakol tamei": but if there was a non-Jew with them on this break-in, or a woman, everything is tamei. This is the counterpart of the clause at the opening of the mishnah. A non-Jew is treated by the sages as though he carries the tumah of a zav, and a woman who is an am ha'aretz, who is not careful about these laws, is presumed to be a niddah. Either one conveys midras tumah to whatever he or she sat or lay upon, so once such a person was part of the group, nothing in the house escapes.
The practical summary of the mishnah is not complicated: a collector who comes in has touched everything, a thief has touched only what stood in his path, and the moment a non-Jew or a woman is part of the visit, the entire house is affected. May we all be spared the need to apply any of it.