WW2 is viewed differently in Asia
The political situation in Asia before WW2 was shaped by old Euro-centric colonial powers (Britain, US, France, Netherlands etc ...) and one new Asiatic power - Japan. We could also mention the communist USSR, but before the war their influence was limited to China and not that important for this analysis. Anyway, Japan was that new upsetting force threatening to overturn existing order : highly aggressive and wanting to expand their empire, but at the same time offering Greater East Asia Co-Prosperity Sphere and slogans like "Asia for Asians". Views on Japan are highly divided : China lost millions in Japanese aggression, but in countries like India and Thailand they may see them in positive light: the first Asiatic country that decisively defeated some of European colonial masters.
But what about Germans and the Third Reich ? First of all, except for the occasional U-boat, Germany was not involved in WW2 in Asia. This fact alone shapes the opinion about them a lot: everything people in Asian countries know about them is from secondary and tertiary sources, they do not have a collective memory about Germans, German occupation, German behavior etc ... From textbooks and documentaries they know that Germany was allied with Japan, and that they fought against British, Americans and French. Thus, what people think about these countries reflects on Germany in a diluted manner: for example, considering Thai history in WW2, they may view Japan somewhat positively, and some of that reputation transfers to Germany. Chinese opinion on Japan is the opposite, but on the other hand Germans did supply some equipment to Chinese, so the look of German soldiers with the famous Stahlhelm may endear them to Chinese etc ... As for German atrocities in the European theater, well, Asian people have their own dead to remember. This includes not only WW2 casualties, but also casualties from subsequent wars (Korea, Vietnam etc ...) and calamities like the Great Leap Forward or the Khmer Rouge rule.
What about Third Reich imagery ? As we explained, people in Asian countries do not have great emotional attachment to the European part of WW2. Therefore, for them, such imagery could be just another exotic thing or part of the fashion - similar for example to someone in Czech Republic proudly displaying the Rising Sun Flag, which would be a grave sin in China or Korea. There is also a "cool rebel factor". National-Socialist Germany lost the war, and a present mainstream political system on the world stage is categorically against them. Therefore, someone wanting to display that they are "against the system" could effectively do that with T-shirt displaying Hitler or a necklace with the swastika or the Iron Cross. Except for the occasional tourist, it is highly unlikely they would encounter someone who would have personal reasons to oppose such imagery . Finally, and often overlooked is a fact that the swastika, while reviled in the West, has a totally different meaning in Asia.