Question: How does R' Aaron know what's going on by his brother's factories? Maybe you want to do a post about which factories do/don't check צומת הגידין? (Agri doesn't have any "Tzomes issues at this time)
The satmar Butcher on 82 Lee Ave is under the auspicies of Reb Zalman Leib's Rabonim. They get their poultry from Marvid (CRC-Hisachdus) and from Empire-Alle/Meal-mart (Nirbarter & OU).
The system of checking for tzomes hagidin at the Empire/Alle/Meal-mart in a nutshell, they check the first 100 or so & if there are less than 2-3% (shishim is 1.66%) of problems they don't check any other ones. [Note: there is no bitul after the feathers are removed.] There were chickens checked in the case by the customer & there were "tzomes" problems.
That's in short the reason that Reb Ahron (Satmar-Monroe) claims that his brothers chicken are not properly checked for צומת הגידין
Therefore when purchasing poultry at the satmar butcher stores in Williamsburg, Borough Park, etc "specify-No Alle/mealmart, only Marvid".