I had the same reaction that most fans had when I learned that Overeem failed his drug test. I wasn't pissed that he "deceived me", I was(am) pissed that the fight was off. We had the two best strikers in the division battling it out for the title in addition to a full HW card. When it turned out that Overeem actually had tiger blood that great card started crumbling in front of all our eyes. In Dana's first response to this news he said he was "beyond pissed" and that is because this is deeper than one card.
Almost a year ago I wrote a fan post about Alistar Overeem being the UFC's next big thing. It was before the Werdum fight which turned into a train wreck. However, Zuffa saw the potential and then finagled a way to get Alistar into the UFC and put him up against Brock Lesnar in the biggest PPV of the year. Overeem went out there and dominated Brock and then disaster happened. Brock Lesnar had enough of MMA and retired. I'm sure Dana, Lorenzo, and Frank all saw hundreds of millions of dollars just floating out of the cage. There was one great result.
Even though Brock retired it seemed like beating Brock helped put Alistar over. Many people said that "casuals" they were watching UFC 141 with became Overeem fans after that fight. It wasn't a surprise. Overeem is a promoter's wet dream. He is a muscular and intimidating heavyweight who uses striking to beat his opponents. If half the fans of Lesnar went over to Overeem then they'd be looking at 700K buys at minimum for whenever Alistar Overeem fights. This card was going to be a proof of concept of that belief. Furthermore, I do think that Zuffa was hoping that Overeem would win that fight since he is much more marketable than Junior. It is the same way that they were clearly rooting for Cain "No Known Weaknesses" Velasquez to beat Junior "He Gets Tired" Dos Santos on UFC on Fox 1.
So this positive test is a worst case scenario for the UFC. Overeem had the potential to be the biggest star in the UFC. Now he's officially tainted as a "steroid user" even if he gets off on some technicality. Zuffa still holding out hope for the fight shows how much they were banking on Alistair. I'd bet that if JDS were the one to test positive they would have stripped him of the belt by now and inserted Mir in there in hopes that Overeem puts him on a highlight reel.