Ironically, I had a call like this today. She was calling for a party for 30 and asked, "Do you have cakes on hand that I can come by and sample?" I said, "I'm not a bakery ..... my items are made to order only, so I don't have cakes just sitting around. And I only do samplings for orders for 100 people or more."
She said, "Oh."
I have a minimum serving requirement for a free consultation/tasting. If you are planning for under the minimum, there is a charge. I need to cover my costs (especially my time), because if I do a consultation/tasting for every cake, I am losing money. A consultation for a cake for 30 peeps? Forget it, but they are welcome to stop by the shop during opening hours and they will get personal attention from me, and I will answer their questions etc.