Boosting for gold (Is it legal)

Is it legal to boost people for gold in low level dungeons?

on whatever server on wotlk?

Why wouldnt it be? Anything paid with ingame currency should be legal, thats why we have it for. Doesnt matter if you pay for a flask or something else.

There is some restriction on boosting in Arena

You can do boosting for gold until people find free boosting services. Then they gonna mock you up.