Are you kidding me? For one example, see American Express's Merchant Operating Guide https://icm.aexp-static.com/Internet/NGMS/US_en/Images/MerchantPolicyOptB

Are you kidding me? For one example, see American Express's Merchant Operating Guide https://icm.aexp-static.com/Internet/NGMS/US_en/Images/MerchantPolicyOptBlue.pdf https://icm.aexp-static.com/Internet/NGMS/US_en/Images/Merch... See section 10.2 Prohibited Merchants. There's a whole list of them. Here's a select few: Multi-level Pyramid Sales, Prostitution, Payday Lenders, Timeshares, Gambling, Virtual Currency, Escort Services and Non-Licensed Massage Parlors, Mortgage Payments.