Putting a dollar bill in your direct mail advertising was a great gimmick when people started doing it. There's a lot of energy in physical money, and for awhile it was a terrific way to attract attention. Some marketers even used $20 bills for certain highly targeted campaigns. One high roller is reputed to have used $100 bills, sent via FedEx, in a mailing to CEOs.
$100 bills probably still work. (And if you have the perfect message for the perfect list, it might be worth it.) But at this point, $1 bills tell your prospects "this is junk mail." They pry the bill loose and the rest of your piece goes into the recycling bin. $1 isn't enough to make a piece of mail remarkable any more. On to the next gimmick.
Are gimmicks intrinsically wrong? I don't think they are. Gimmicks are used to get our attention, and in the world of information superclutter, a good gimmick is not to be despised.
Seth Godin has a nice quick post about the difference between something remarkable and something that's just a gimmick. Godin says that "if a product or service adds value for the consumer, it's not a gimmick," although I might have edited that to say "it's not only a gimmick."
Cool stuff vs. cheap tricks
I was at a copywriting workshop last night (I realize I have a weird idea of fun) and the presenter was going through a stack of large-format postcards he's received from real estate agents. I don't know who the vendor is who provided them, but they all looked pretty well exactly the same. Front of the card, large format stock image with some kind of an attention-grabbing point. Back of card, photo of agent with contact info and maybe a tag line.
The presenter ran through the stack, evaluating whether the front was interesting enough to cause you to turn the card over, and then whether there was anything on the back that conveyed benefits to the reader. Fair enough.
But the larger point is, when you see one or two of the same postcard every day, it turns into wallpaper pretty quickly. It barely matters how good the gimmick is on the front of the card. If you use the identical tactic everyone else does (because the vendor did a marathon telemarketing campaign to you and your competitors last month, or bought your name on a list with 50,000 other people in your line of work), there's no talk value.
A purple cow isn't remarkable if it's in a purple herd
If marketing sin #1 is "don't be boring" (I'd probably put it at #2 or #3, but it's right up there), then a boring gimmick must be the greatest sin of all. Cheap tricks need to be interesting or they're just cheap.
A remarkable gimmick, if there can be such a thing, is relevant, useful, and interesting. If you're spending dollars on materials that don't live up to that standard, Quit.