That’s what happens LOADS of time while discussing requirements.
<P O> I want a Pink Pony!
<P M> Ok, what that pony is supposed to do? Does it walk? Does it run? Which kind of user would ride it?
<P O> Oh well, not sure, a pony is cool and cute that’s what important! Ask Marketing for the details.
<P M> According to the information from marketing and design the average use would be a big adult, carrying swords, pikes and shield called Knight. You need a Steed not a pony.
<P O> But but, PINK, my daughter loves pink!
<P M> According to the current poll among the Knights the top colour is pitch black. Your target user wants a Black Steed.
(A longer version will appear sooner or later)