I don't really see how that's disgusting... I mean, do you go out anywhere? I'm sure you've touched worse bacteria while at work and then touched your mouth or face after. You should be more worried about that.
I'm sure people aren't using it between wipes so I don't really see how it's disgusting. (At least not with the same hand)
It is just the thought that something could go wrong and the iPad could catch some dirt
Anyway, the iPad can be used almost anywhere, so I guess if someone wants to use it on the Toilett he/she might as well do it. I don't use it like this.