Recently I was at a tourist attraction and a stranger asked "would you mind taking a photo of me?" I normally agree to do this, but in this case I decided to refuse. (I think the reason is not relevant here.) So I replied: "Err... yes, actually I would, sorry". Well, the guy gave me a weird look and said "thanks a lot!" (sarcastically, I presume).
So it probably wasn't the best way to refuse, but I wasn't ready for the interaction (as usual) and was also put off by the form of the question: "would you mind..?" where "no" means "yes" to the request and vice-versa! But even thinking about it now, I can't see a good way to phrase it, so that:
1) The refusal is clear
2) I don't lie about anything (actually even the "sorry" felt kind of wrong, because I wasn't, really)
3) I don't give reasons
4) It causes minimal offence
Any ideas? Basically, what I wanted to communicate was something like:
I'm not passing any judgement on you as a person and there is no hidden message here, but I'm simply unwilling to do the favour you asked of me, for reasons of my own, which I'm unwilling to discuss with you.