As a practical matter, that means no illegality, and if there was no illegality, then the only conclusion that can be drawn about the advice given is that it was damn good.
As for what is ethical.....lawyers are paid to advise their clients on how to skirt the edges of the law. That is their job, and their ethic.
Which is the biggest reason the bar associations should do nothing. You don't disbar the other guy because he out-lawyered you. Even Anti-Republicans generally have a split hair's breadth greater integrity than that.