“How can you detect a power supply unit that does not have a slow power drop?”
I personally use a hobbyist’s tester called a “Watts-uP” (wrc-electronics-usa.com) inline (between the power unit and the Dreamcatcher) with the power unit. It will log the sag in voltage over the period of time power is applied and you can read it directly while it is connected and powered on. With the Dreamcatcher, if the sag is lower than 4.98v, you will experience freaky things.
Normally due to the inexpensive nature of these items, it is best to just purchase a power unit with a proven track record, such as the official Raspberry Pi power supply, or PWR+ TBAM3-ul. I have used both of those with good success on the Dreamcatcher.