Perhaps if more had paid attention in Muggle Studies class, they would not wind up in such situations. Though even then, there are more than enough Muggleborn and Halfblood persons who are familiar with the other side of the divide to give advice as need be.
However, no amount of information can save those who know but are simply fashion inept to a terrible degree.
I fear I may need to replace a set of robes that came by an unfortunate accident. Would you have any openings this week?