Wrong way to advertise in a feed

The entire Hack-a-Day feed just showed up as new in my aggregator. Every single item in the feed was sitting there, appearing as unread, waiting for me to read them. I’d already given them my attention once, but now there were thirty feed items stretching back to November 12, begging for my attention again.

Feed readers often work using change detection. When the list of items in a feed changes, anything that wasn’t there before is considered new content. When the contents of an item change, the reader marks it as changed, or depending on what changed, perhaps even determines the item is new. By default, new and changed items show up in your reading list in most readers.

The most common cause of an existing item changing is the author updating it, perhaps to correct a typo or to add more information. Sometimes I see entire feeds show up as changed when the publisher of the feed changes their feed’s format, going from partial items to complete item bodies. Feeds that switch to a feed management service like FeedBurner or Pheedo or that add tracking information to their feeds will usually end up with a whole slew of repeated feed items. And when someone adds AdSense for Feeds image tags into their feed for the first time, everything in that feed shows up again in my reader.

Hack-a-Day added an advertisement to their feed. Every single item now contains a short paragraph at the end about plasma TVs. The ad was inserted as plain text, and because it went on every item, it caused every item to re-appear in my reader. Most likely what they did was edited the system that generates their feed and told it to stick this text ad at the bottom of every item. Later, when they have a new sponsor, they’ll change the ad text, causing everything to show up as new yet again.

This is obviously the wrong way to do things. If you’re going to have a regularly changing sponsor for your feed, there’s a couple of ways to do it without alienating your readers.

Put your ads in an item by themselves. Instead of attaching the ad to an existing item, create a new item that contains nothing but the ad. Then when you change the ad, only the ad item will appear as new in the reader. The remaining items will remain unchanged. See any of the Lockergnome feeds for an example of this.

Put the ads only on new items. When you publish a new item, attach the ad to the item body instead of appending it to your feed item template. Since the ad appears only as items are published, previously published items are unaffected. If you do this, never remove an ad that’s already been attached to an item. Removing the ad will cause the items to reappear in a reader.

Typeset the ad in an image. By setting the ad in an image, you can change the text inside the ad without the contents of the feed changing. Use a static image source like ad.jpg and just change the contents of the image. Since the HTML never changes, feed readers won’t ever notice the ad has changed, so existing items won’t show up again.