I'be been to the DragonFruit festivals and tried the magenta fleshed fruit and although their are one or two magenta/dark red fleshed fruit that were sweet and delicious, most were less tasty to me than the purple fleshed fruit.
Lisa, if I remember is a nice round fruit of dark red color like blood. It's positives are that the flesh was extremely firm and there was a very good amount of acidity. The negative is that it was not very sweet, and my wife said it made her tongue feel strange.
Other red varieties I tried at the festival or that friends grew had some good acidity but again lacked sweetness. Zamorano was in this category. I cannot remember a bad tasting purple fleshed Df that I have tried. Yes there were some purple fleshed varieties that were picked early or overwatered or grown in too much shade or not fertilized properly but most still had decent Brix, the lower Brix was definitely much more bland.
All of the DF that tested around 20% Brix had wonderful flavor. Yes, some may say it's bland like a good watermelon can be but it is also extremely refreshing and cooling. I don't know if anyone else notices but I feel great after eating DF, perhaps it helps regulate blood sugar levels? I hope all those that said DF is Bland can try a 20% Brix purple fleshed fruit on a hot summer day.
Simon