@Ann ********
This was before covid back in 2019. It was a crabby immigration lady at DMK I later heard stories about that she has a reputation for making reasons to hassle people. Unfortunately I didn't have all my documentation ready which could have smoothed out the situation. While she said I was denied due to "too many visas" she seemed to presume I was working illegally and told me not to come back for a year, and only with a work visa. I read the stamp she put in the passport which actually said I was denied for not having
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baht cash on my person. However, since then I prepare extensively by bringing
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cash and tons of documentation. DMK/BKK are known for this entry risk if you have a lot of visas.
There is a "Fast Track" service offered by Thai Visa Centre you can pay for in advance to ensure you will have no problems on arrival. They check and approve your situation before you travel. I have used it and recommend it if you want to come through BKK/DMK. That's probably the best option if you're coming from Taiwan. (Note that other companies offer a cheaper fast track service but they don't do the preapproval, just the accelerated processing line.)
I have heard that entry through Phuket, Surat Thani, and other regional airports are also easier than Bangkok. Tourist island airports like Samui or Krabi also have a reputation for easy entry but the flight prices are higher.