Ethics and "Feels Wrong"

I had a situation where I couldn't find an ethical rule preventing me from something. I can't go into details. But I ended up doing it anyway, because it's what my client wanted. I asked my supervisor's supervisor and it was basically "what rule do you think it's breaking?". The one I picked was a super stretch and I said that much.

I've been a PD for a bit over 5 years. This is the only time something felt wrong that I still needed to do. (Aside from normal things that society thinks is wrong, but we know it's not wrong, like representing a pedo).

How often do other PD's run across this situation, where what you do feels wrong but isn't ethically wrong in the legal field?

For me to feel this way, it's morally wrong. On the scale of things, it's not that bad, but it doesn't change the turmoil I had trying to come to the decision.