Everyone has a different opinion about them. I think that adult babies enjoy childish designs (like blocks) while diper lovers like them either blank or with very special markings (like paw prints or rainbow tapes). Blank ones are also reminisent of the older diaposables from the 1970s and 1980s.
Examples of blank diapers include the Dry Care 24/7 and the Bambino Bianco. One example of a diaper with non0childish markings is the Abena Abri-Form (all models). These have a size stripe, dual wetness indicators and a center stipe resembling a DNA ladder with only a single helix (they call me Science Dog for a reason). I can understand why the size stripe would be practical and the wetness indicators are wuite effective (changing from yellow to green to blank). That DNA ladder always puzzled me though. I guess it's to make it eaiser to put on and center it.
From what I know about the adult diaper market, they requently try to aviod calling them diapers. Instead calling them diaposable underwear, breifs or incontience pads. They are almost always white to look more like normal breifs and are only branded with markings that are needed. What do you think about the purpose of certian markings? Are they nessary or just a crazy idea?