The German Federal Court of Justice (BGH) recently rendered a decision on trademark use in the field of textiles that is worth reading.
In general, use as a trademark requires that a significant part of the relevant public recognizes a sign as indicating the origin of a product. For that, it is not sufficient that a sign is originally distinctive and that its use is not plainly descriptive. Instead, use as a trademark has to be assessed in each case individually taking into account all circumstances of the case. Thus, use of a first name like “SAM” as a model designation can also constitute use as a trademark and, in consequence, be deemed trademark infringement.
Read more about „Model: Sam“ - Use as a trademark or a simple model designation?