The national sorority suspended the local chapter because of the shenanigans; and PSU itself, in a very nicely worded message from the president, supported the rights of the individuals to self-expression and at the same time pointed out the obvious (to me, MrB) insensitivity of the costumes and the signs. As to the difference between the first two links and the third--again, to me it seems obvious. First, the first two represent people who are what they are represented as being; in the third, there are people putting on costumes to represent an ethnic other. A parallel might be for the young ladies to have put on black face. The ethnic other represented by the young ladies is also, quite deliberately given the signs that they are holding, intended to be an economic other as well. I don't know the young ladies, of course, but if they're free to make blanket insinuations about the ethnic other, then I can make blanket statements about them: all of them are spoiled rotten rich bitches who've never had to work harder than clipping and painting their toenails, and they are mocking physical laborers as lazy, indolent, pot smoking members of the lower classes.

So am I being harsh in describing the young ladies? Sure.
MACTECH ubi dolor ibi digitus