"Oh, yes?" he asks, raising an eyebrow. "We aren't, then, talking about a subject population of habitual coffee-drinkers, I take it. And the comparative difficulties of adulterating white and black liquids without changing the color have nothing to do with it, naturally.
"And, no, it's not; no one drinks sludgy orange liquid until they've been inured to the idea. Except that children will drink practically anything as an alternative to water. The flavors of the pumpkin juice and the potion enhance each other, as it happens--ask any recent graduate; they'll tell you that pumpkin juice found outside of Hogwarts is 'too sweet' or 'missing something.' Furthermore, melons are always worth consideration in any spells relating to attraction and fertility, and pumpkins in specific are a catalyst to many such effects. I will admit," he finishes, "that orange is a thirsty color, and that people do tend to drink more of orange liquids than of other colors, once they can nerve themselves to start."
"Orange... people?" he asks quizzically.
With a trace of indulgence, "Just as you like. No doubt whoever you ask in the end will have more faith your motivation if you've researched the subject thoroughly beforehand, in any case."