Switzerland is a highly diverse country given its small size. The three main language regions (German/French/Italian) are culturally oriented toward their same-language neighbors, so a fad in Germany might not even be known to the French-speaking population of Switzerland.
Furthermore, there is a noticeable cultural divide between cities and the countryside; products that may be acceptable to sell in a city may not be well received in the countryside.
The foreign population can also be segregated to different language regions.
In short: If you consider opening a store, you should do thorough market research to identify where in Switzerland the store should be located.