I'll probably get hammered off you guys for saying this, but if you sell a modded Wii to someone without specifying that it is modded (and could therefore get bricked), isn't that wrong?
I mean, they could track you down, report you to whoever and even get you for fraud. Fraud being that you knowingly left out details of the item you were selling.
I know a lot of people would want a modded Wii, but I'm sure there are just as many out there who don't want a modded Wii.
Even if you 'hint' at it being modded, I know that I myself have never heard of this 'duck whistle' rubbish before, thats really not enough. You should be making sure that the buyer knows what they are getting into.