Rule 9-6-4-e states that "It is illegal participation: ... To use a player, replaced player or substitute in a substitution or pretended substitution to deceive opponenents at or immediately before the snap or free kick."

Furthermore, rule 9-9-3 states "Neither team shall commit any act which, in the opinion of the referee, tends to make a travesty of the game." While that doesn't directly address your play, I believe that every rules board that has reveiwed these types of plays where players act as if they are leaving the field, has determined them to be illegal. In fact, I believe the case book adds something like this to its comments about rule 9-9-3:

"Football has been and always will be a game of deception and trickery involving multiple shifts, unusual formations and creative plays. However, actions or verbiage designed to confuse the defense into believing there is problem and a snap isn't imminent is beyond the scope of sportsmanship and is illegal."

And, yes, your college coaches were correct - it certainly is bush league.

Perhaps poor coaching caused the play to work (poor coaching also caused the play to be called in the first place ), but it is still illegal. It is what it is (i.e. illegal) - it's really not open to debate.