In My experience, Asmodeus is GREAT to work with for spellwork IF:
you are trying to achieve something that you personally are very "FUCK YEA" about. If you don't feel the desire for the goal down to your core, it will at best have a very weak effect. If you incorporate sex work into the working for a goal you don't really care about it's likely to all fucking shades of sideways.
It is something "paid for" in some way.. (e.g. My hotfoot always includes payment - typically a penny per day that I charge the Hotfoot, paid via water disposal of the excess and the container - not very environmental I know... if you have a better way, let me know). Sex Magick can very easily include its own payment - I have found orgasms in tribute Asmodeus to be a lovely offering of payment to him. Paying Asmodeus for the spellwork will not change any Karmic effects of the things that happen due to the working. As much as posible you should only use curses/hexes cautiously, defensively, and in similar 'strength' to the wrongs you are seeking atonement for.
It is something that a loophole can't be twisted back onto you. I recently did a...we'll call it a "may you step on a lego every time you get up in my business", on someone who Could have a negative effect on someone I hold very dear, and is KNOWN to be a bit of a Nosey Buttinski. Well, things much worse than stepping on a lego happened to the person I hold dear, and that minorly inconvenienced the person I did the binding/reflection on...I Karmically covered my bases, not wishing real harm on the object, but I didn't put payment into the work, and I didn't protect my interests well enough, so it worked, but with unintended consequences.