For me it is when companies/services market themselves as donating to XYZ cause if I buy their product. If they want to donate, they should have already done that with the money they have. Asking me to give them profit so that they can donate is so obviously pretentious.
My kids are picky eaters. Getting a free sample at the ice cream shop has prevented many bowls of wasted ice cream.
But I can’t think of any other situations.