Dragon fruit can be grown in California, Florida, and Hawaii and is not "bland mush with tiny seeds that can require floss to dislodge". The author must have had a bad one. They can be extremely sweet. The seeds are so small that they go down without noticing and I've never had to use floss. My favorite is a variety with deep red flesh. Mangosteen is so far from its depiction---"to eat a pile of mangosteens is an exe…
If you can pick your own, though, they're in my experience pretty avoidable: go for ones that are purple, not black, and avoid any that have traces of yellow leaking from the top.