Should Merchants List Expired Codes On Their Own Sites?

"Purple" (Martin Warn) pointed out that BuyAGift was #1 for "Buyagift Discount Code" which got me thinking ...

What would happen if merchants started creating pages about the avaliable discount codes on their own site, but maybe didn't make a big play of it on the site itself? How many merchant sites would appear 1st for "[merchant name] discount codes"? And what impact would that have affiliate sales driven by the discount code mechanism?

Also to prevent unscrupulous affiliates knowingly promoting expired codes as a cookie-cutting excercise, should merchants list all the codes and optimise for them on their sites?

I reckon tonnes of commission could be redirected back into merchant coffers this way - but would it be a good thing? Personally Thortons' 15% discount code helped generate bucket-loads of sales for me and I would probably had lower conversion rates without it.

So, a question for all you affiliates, merchants, networks etc; should merchants use their own sites and optimise for expired discount codes, and in the process redirect a degree of relevant discount traffic away from affilites as a by-product?

Or should we view the situation that this is just another sales-mechanism us affiliates use that will ultimately be closed down by merchants for their own use?