A FlyerTalk Posting Legend
Join Date: Jul 2002
Location: MCI
Programs: AA Gold 1MM, AS MVP, UA Silver, WN A-List, Marriott LT Titanium, HH Diamond
Posts: 53,012
It isn't illegal anywhere that I know of.
Whether it is "wrong" is opinion.
It definitely is against the terms and conditions of the FF programs.
Trading certificates/miles in Coupon Connection is no more or less right or wrong than selling them on eBay.