It might be best to assume that a customer is asking things with the best of intentions, and only take offence when it is beyond reasonable doubt that something is meant to be offensive. Even then I would reply as if no offence was meant, in order to diffuse the situation and show the world that you can handle difficult queries. This is how I talk to clients, but also to everyone else in life. Losing one's temper is never beneficial, not for me, and certainly not for the client.
For what it's worth, it was Clapeyron's praise and his many pictures of Luxire trousers that convinced me to order trousers myself. I understand we can be a difficult bunch, being obsessed with details, but in the year I've spent on this forum I've come to understand that 99.9% of the members mean well. Germans and other northern Europeans, such as the Dutch, can be a little direct, but it is merely a part of our culture, and should not be seen as rudeness.
EDIT: Spoilered because this was posted at the same time as Luxire's reply. Let's consider the matter dealt with.