Where can I find some glitter dust?

Hint 1 of 11:

Rincewind will actually give you a pretty big nudge when you find the glitter
you need.

Hint 2 of 11:

Celebrities are known for being glittery.

Hint 3 of 11:

Or even want-to-be celebrities.

Hint 4 of 11:

Look at the milkmaid's dress (she's in the Plaza).  That's pretty glittery.

Hint 5 of 11:

Does the milkmaid remind you of any real celebrity?

Hint 6 of 11:

Like Marilyn Monroe?

Hint 7 of 11:

She was famous for a scene where her dress flew up when she was standing on
an air vent just like the one the milkmaid's standing on.

Hint 8 of 11:

You're going to have to help the milkmaid's dress in the game, though.

Hint 9 of 11:

Look for the underside of the grate.