When I present people with the case against the sham and Chillul Hashem and grievous error known as “Mechiras Chametz”, a common last refuge is bringing up the Bittul.
It’s only a rabbinic problem (not that there’s any הם אמרו והם אמרו), even if the sale is a complete farce, they contend, since everyone does Bittul Chametz, anyway.
Besides (in a seeping, sweeping self-reckoning), do I even sell Chametz Gamur? (Well, oh right, the whiskey and Marmite and VWXYZ…)
Rabbi Yitzchak Brand responds (abbreviated and paraphrased from his landmark treatment):
How can someone declare they regard any Chametz still left in their possession as worthless if they are also actively selling that same Chametz?! (It makes not a whit of difference when the “sale” and Bittul occur, or if he does the Bittul both before and after — unless he buys his Chametz back before Pesach; it is davka the Bittul that suffers here.)
“I want this utterly worthless Chametz begone yesterday! But I also think it’s worth good money…”
Don’t say: “OK, well, it can’t hurt”!
Actually, even though the sale is invalid, it does have the negative effect of canceling out the Bittul, since the seller announces that he does desire the Chametz, and that no one may go near it without actual full payment, etc. (whether Bittul is working on Hefker or on משוי כעפרא). (Also, see the Rishonim here p.40-44.) So, the Torah prohibitions of holding on to Chametz on Pesach do not become derabbanan!
There is no middle ground with a sale. Either the personal property belongs to the seller, or it transfers title to the buyer: ובלבד שיתננו לו במתנה גמורה. It’s not a Matana. It’s not even hefker. Meaning the Chametz is still in your possession and Mede’oraisa.
Those rabbis going around with the Goy for surprise visits on Chol Hamo’ed still have the Goy pay for the Chametz he takes. (So what if it isn’t Chamas? Even a shopkeeper has the obligation of “Tashbisu”.)
OY VEY!
If you can’t bear the monetary loss of keeping the Torah, better שב ואל תעשה thereby merely transgressing the original Torah prohibitions than to both transgress the original Torah prohibitions and also add the horrible, terrible, no good, and very bad “Sale” of your soul.