I had a shop "accidentally" charge my foreign visa card in USD today despite my making it very clear that I wanted to be charged in baht and their insistance that it would be. I had them cancel it and rerun it in baht. This means I got to see the very clear difference on my pending transactions. I also took a screenshot of transferwise and the rate reported by google at the same time for comparison. I thought the data might interest some people here. Really can't beat just using a credit card in terms of exchange efficiency, assuming you can find a bank that doesn't markup the rates from visa.
TLDR : Answer Summary
The poster discusses an experience with a Thai shop charging their foreign visa card in USD instead of the desired baht, highlighting the importance of confirming the currency of charge to avoid unfavorable exchange rates. They suggest using a bank that offers good rates without markup, specifically mentioning Capital One as an option.