Turn Everyday Items Into A Gold Pile.

[ResinMic]

guess its bannable.

[jumperu]

It's the same thing as this Underused Advertising Opportunity | Just My Two Copper - WoW Gold Guide .
And as far as i know, and how all those comments point, it's called scamming and it's bannable.

[Sliptree]

I would probably say to not do this on your main, since as you said someone is bound to catch on and then it turns into a one-shot wonder. When they do figure it out, and chances are they will what with Undermine Journal being widely available, I'd want a character who doesn't appear to be connected to the one I play by a couple degrees of separation, lest my reputation on said server get shot to hell.