Respecting Divination Tools

I can't find it offhand, but I'm sure I posted some time ago about playing a card game with a friend's tarot cards and having the strange experience of the game just going on and on. Of such things is created folklore of the sort where someone doesn’t treat an entity with enough respect and it bites them in the bum.
I find it very interesting the way experienced magical people talk about magic as if it is a thing in itself, and so treated as if it has a certain autonomy. I suppose this could be paralleled by the way you sometimes hear people talk about electricity as a bad master, and something to be treated with care. In just such a way the tarot is something to be treated with care, and also similarly to electricity it just keeps on giving.
The need to treat the tarot's gifts with respect was reinforced to me only this weekend when a colleague who knows I'm into any amount of weird shit, asked me to read his cards. I didn’t have any with me so when I told him so it happened to be true. But now I'm faced with the quandary that I'm never going to be able to read them at all because when I got home I drew some cards for him.
I have actually never seen it so clearly but a picture of childhood sexual abuse, which has left him fairly screwed up for life, appeared as clear as a bell.
Obviously this means that now I can never read his cards and am going to have to keep making excuses...