Border Enforcement, Security, and Trade (BEST) Facilitation Act of 2023 This bill establishes positions within U.S. Customs and Border Protection (CBP) to review inspection images of vehicles and cargo entering or exiting the United States. Specifically, the bill establishes the position of image adjudicator within the CBP Office of Field Operations. An image adjudicator must (1) review nonintrusive inspection images of vehicles and cargo entering or exiting the United States; (2) assess whether such vehicles and cargo contain contraband, illicit drugs, weapons, or persons seeking to unlawfully enter the United States; and (3) refer suspicious vehicles and cargo for further inspection by a CBP officer. The bill also establishes the position of supervisory image adjudicator with additional responsibilities, including receiving and reporting intelligence to the National Targeting Center about techniques used by malign actors to transport contraband, illicit drugs, weapons, and persons seeking to unlawfully enter the United States. The bill establishes annual training requirements for both image adjudicator and supervisory image adjudicator positions, including training on privacy and civil liberties and how to analyze inspection images. Within a year of this bill's enactment, CBP must develop a workforce staffing model for these positions. The Government Accountability Office must validate the model within six months of the model's completion.