Many people have a custom to bake a "Shlissel Challah" the Shabbos after Pesach. This is a challah baked in the shape of a key or with a key inside or both. It is supposed to be a segula for parnassa because the "key" to parnassa is in only Hashem's hands [see beginning of maseches taanis/tynis]. I heard a shiur from a YU Rosh Yeshiva where he said that it is אסור מן התורה to bake such a challah because it is ניחוש [forbidden superstition]. Of course I have great respect for this Rov and he is certainly much greater than I [me? both?] but since this custom is mentioned in the sefarim hakdoshim [see for example מנהג ישראל תורה ח"ב סי' תצג] and is practiced by thousands of Jewish women with no objection from prominent poskim, I would have preferred if he would have been מלמד זכות on this custom. I also read an academic paper which showed its historical paganic roots. Despite this, I think that the bakers have a solid halachic basis. But since it requires more research on my part I won't talk yet.
In general, it is sooo nice when rabbonim try to justify practices which seem on the surface to be problematic. An example of such a sefer is the שו"ת ארץ צבי of Rav Aryeh Tzvi Frommer [Rosh Yeshivas Chachmei Lublin]. Among other things he tries to find a basis for the Chasidic practice to daven NOT EXACTLY bi'zman. He is very creative and his sefer is worth owning and learning. I would tell you that I have recorded shiurim based on his sefarim but I don't want to advertise:-). [I know of another sefer where the author - a gadol bi'yisrael - always seems to try showing how what everyone does is wrong.]
Of course if there is no justification then they must condemn the problematic practices. An aveira is an aveira.
But I don't think the shlissel challah is.
Later addendum - See Shu"t Chaye Halevi ח"ב סי' נד. Neither does he.
