Actually, that statement is about 80% true.

In my experience (which is about 15-20 times a year) one of the biggest things the idiots behind the counter care about is what you purchased, and what country the purchased items were made in. I had no idea until about 5 years ago there was actually different duty rates dependent on the country where the goods were manufactured. When I was living in Montreal I did some shopping at a Ralph Lauren store in Vermont and had shirts that were the exact same price but were taxed differently because of where they were made.

As I have said earlier, it's not very often I actually purchase things abroad but I find it easier to just lie and say I did so I show a value in the all important box that asks how much you have spent because they don't believe you when you say nothing.