Part of the reason they make me laugh my ass off is the context they are presented in. Inserting Mr. Biznass into the middle of a mega violent monster slaughter piece serves to let up the tension. Scott's use of humour brings our sensibility back towards a more normal level so that he can then proceed to scare the shit out of us again. I suspect that if the humour were not present, we might become inerred to the violence and get desensitized.
I doubt either Mr BizNass or Pookie Chang would make a good stand alone novel. Now a Bloodcast story or two, I can definitely see. And there are plenty of other characters in Scott's books that he could do this with. He creates so many rich characters that he's got a cornucopia to choose from. That's why Earthcore II isn't going to be out until 2013. Totally lost it when Scott called himself a douche in the DRS interview. Frakkin' classic.
GirlCo: Quieter than ninja, faster than Sklorno, stronger than Ki, and more devious than the Quyth
Prøducer øf Døøm, Høst øf Tuesday Terrør, Funky Name Brutha, Retired Gutter Brethren & Tangential Tyke