Trick or gimmick plays should not be used on a regular basis, ie one per game. The definition of a trick play is, your normal offense is sucking so you have to catch them off guard and do something out of the ordinary. A fake punt is a trick play, thats why it is done on 4th down, the punting down, because if your offense was producing yards you would not have to convert on 4th.
Trick plays are something you go over in training camp to introduce them to the team. But do not use up practice time in the season to prepare for.
When ever I see a trick play I see a team struggling for something to go their way.
I remember Ty's last time playing USC before he was canned. He came out with all kinds of stupid rink-a-dink plays....why? Because he knew his offensive scheme sucked. And Diedrick(if I remember correctly) knew it too.
So to in short, trick plays are only planned by teams that have no or little plans. And by teams that have tried everything but are still being shut down.
Me personally, I am glad we have not seen many of them this season.