You can just decline in stores that anyone is allowed to just walk in and shop, but at places that you need a membership for, your membership contract usually requires that you let them look.

my friend employs the sunglasses and headphones technique where blatantly ignore them. They can't touch you, so they just shout a few times, and realize the futility and move on to the next shopper.

The availability of that option depends on your appearance: affluent middle-aged white people can usually do it but if you’re a teenager or match whatever demographic is poor in the area, you have to weigh that versus escalation possibly including armed police response.

Which escalations the store would have to weigh against a loss of business they should expect after racially targeting innocent (if so) customers.

Know your rights and exercise them, keep your chin up and communicate. Fear is a trigger of suspicion.

When has “I’ll never shop here again!” ever been a useful threat? Shops care about people in aggregate, not you in particular. And anyone they decide to bother is someone they already have decided they don’t care about the opinion of.

Especially when it's, say, Walmart which has built a business on crowding out competitors in an area — are you really going to spend an extra 40+ minutes driving somewhere else out of spite? The power dynamic here seems quite unbalanced.

When "I will never" becomes "we demand".

> we demand

Can you name a few, or even one, consumer-level boycott in, say, the last 50 years, which actually accomplished its goal? Accomplished by the actual boycott alone, I mean.

Add up all the businesses that have failed and you'll find plenty that disrespected some of their customers.

Walmart is a much higher bar geopolitically, but bet they have to jump too when word gets out of malfeasance. But it is a prisoner's dilemma when they are the main one-stop value shop.