Product samples would be considered a cost of promotion, so- advertising expense.
Any Products you use personally will not be able to be counted as a business expense deduction unless you can viably say that these products were used personally solely for the purpose of promotion.
For example, you sell skincare products and you can attract new/more customers by using the skincare products yourself and then promoting the brand when prospective customers ask about your "glow" and how you're looking so good!
https://www.irs.gov/publications/p334/ch08.html
