There is an established practice to sell one's chametz (leavened products) to a non-Jew over Passover to avoid the biblical prohibition of a Jew owning chametz during the festival. Unfortunately, often the non-Jewish buyer does not consider the sale to actually be a real sale, and neither do many of the Jewish sellers (who would likely call the cops if the buyer showed up on Pesach asking for his half bottle of whiskey and his bliyos in the cholent pot). This can be a real problem halachically since we have a rule that asmachta lo kanya which means that if there is no real commitment or recognition that one is giving something up for real, the agreement is nonbinding and invalid. (This is one of the halachic problems with gambling where the gambler doesn't really expect to lose.)
This may be the main reason many only sell products that are unlikely to be actual chametz (e.g. flour, vinegar, play-doh, perfumes, etc.).
Likewise, this is the reason Rabbi Mordechai Willig of Riverdale, NY only sells to a non-Jewish lawyer familiar with the concept of legal fictions that are nonetheless binding and further instructs him (informing his congregants accordingly) to drop in randomly on the Jewish sellers on Pesach to pick up some of his actually legally acquired chametz.
Is anyone aware of any other rabbis/communities where the non-Jew actually picks up chametz from his sellers on Pesach?