Asmodia is worried about betting fatigue being a thing, and the extent to which none of them really have much solid information about Keltham the way that Security have solid info about people's secret thoughts... but if Meritxell is willing to step forward and say that she has guesses about some of these markets, Asmodia will set them up. Worst case, nobody wants to bet against Meritxell and things get refunded.
The who-will-Keltham-sleep-with-next market is one that should be run where Keltham can see it, or maybe the previous day's results, and he can tell them how to set it up properly!