1) Well, first, when I say that it always worked during readings, I should be clear that not every joke worked; and the sketch definitely had some evolution from Writing 2 to Writing 5 (when it was clear that it wasn't going to work for the show).
For instance, the first version was messier because I was still learning about heightening. That is, you can't start with a joke about stalkers and then move on to a joke about "lipstick classic" because the stalker idea is so much worse. What you should do is start off small and "heighten" by moving on to more outrageous aspects. (My first version hit the Betty White/funeral joke really soon.)
So, let's be honest: not every joke is a laugh-getter. That's one reason why this sketch didn't move on.
2) My ultimate POV in this sketch was captured by the last line--corporations will do anything for profit. (That's part of the reason why the characters in this sketch are so flat and also named after people on popular bills/money: I didn't want to pick on any particular businesspeople, but on business more generally.)
But the jokes throughout are about how corporations will do anything to make money off of women. So my director asked me to partner up with some of the women in our class and see if we could revise towards that angle.
And... well, not all collaborations are successful. I didn't want to let go of my point (corporations, grrrr!); but I tried to slant some of the terrible comments toward women, which just meant that the ending got too dark too quick: it ended with a joke about murdering women for profit, rather than murdering people for profit. (Violence against people: funny. Violence against women: less funny.)
So we had a collaborative block: I liked my POV, my director liked my premise. That's reason no. 2 why "C.R.E.A.M." isn't in the show.
3) The usual cast for a Second City show is three men and three women. Men and women do play the opposite gender in sketches, but when you can, it's probably better not to ask the audience to do extra imaginative work. (Or only to cast cross-gender for a reason.)
But our cast of Unicorns turned out to be four women and two men. (Why? Because, in the audition process, that's whom we really liked/thought we could write for.)
Conclusion: So now I had a sketch with some funny jokes in it; a strong POV (corporations, grrr!) with a strong but not identical premise (let's get money from women!); and with a mismatched gender cast. And so this sketch didn't make it into the show.
But here's another way to look at it: this sketch was killed by collaboration.
A) If my director had the same vision as I did for the sketch, we could've honed it down to where the POV and the premise matched. (And this is not uncommon: I saw lots of sketches where the writer had funny ideas, but no coherent POV--but the sketch gained a coherent POV through writer-director collaboration.)
B) And if my fellow writers and director wanted to cast the show so as to preserve this one sketch, we could have. (To be clear, we did cast the show with sketches in mind--X would be perfect for my lawyer sketch, Y would be great for your doctor sketch; but the idea of casting the whole show for one single sketch is crazy.)
So what do we learn about sketch collaboration? It's like the reed and the willow analogy people always use to discuss compromise: bend your sketch or lose it.