The shop assistant who says this will not suit you has protected a future visit.

Turning down a sale costs money once and buys something that cannot be advertised. A person who tells you the thing in your hand is wrong for you has just made themselves the only opinion in the shop worth having, and you will come back with a harder question next time. Trust gets built almost entirely out of moments where somebody could have taken the easy gain and did not. Most people feel that difference immediately, even when they cannot name it.

Give one piece of advice this week that works against your own interest. It will be remembered far longer than anything you sold.