Ho Chi Minh update - in case it's helpful to someone else. I went this week for my 3rd 60-day tourist visa. Process was quick and painless, except they wanted one document which I didn't have. Proof of my flight INTO Thailand. I had proof of exit, but not arrival. It was easy to fix with a print shop right around the corner.
TLDR : Answer Summary
A recent experience applying for a 60-day tourist visa in Ho Chi Minh City highlighted the necessity of having proof of entry into Thailand. While the application process was generally smooth, the applicant noted that an arrival flight itinerary was required, which they were able to provide through a nearby print shop.