It's highly unlikely a US company would pursue an action against a person on Denmark for a trademark violation unless it was blatant and of a size and scope where the cost of a lawsuit was justified. In civil law the distinction of 'legal' is often what can be proven in court and makes economic sense. Big companies don't like lawsuits but they also consider their branding and trademarks as valuable corporate assets that should be protected. Bottom line is that most companies won't go after individuals for single case infractions since they have much larger fish to fry.
So to answer the question: It's not legal to use a companies registered trademark for any purpose, but the company is faced with the burden of showing material harm and defending their trademark or intellectual property. In civil law the amount of harm needs to be at a level that the cost of legal action is justified. The usual first course of action from the company is a "cease and desist letter" that tells you to stop. Saber rattling (warning shot) but usually effective.
Disclaimer: I am not an attorney but I have been thrust into the civil legal system several times and paid $$$ to "learn". Bottom line is that the person with the deepest pockets or best lawyers wins. I have sit in meetings in a Fortune 500 company with their internal legal staff about using legal actions and I can tell you that it's largely an arbitrary process. It's hard to predict what the CEO will elect to carry past the canned warning letter stage.
TOM CAUDLE
www.CandCNC.com