Like Dave, I also do a lot of skimming when reading RSS. I’ll quickly scan the headlines, then read the first sentence or two when I find something of interest. If it keeps my interest longer than that, I figure it’s worth a click, so I don’t mind clicking through to the site to read the rest of the story. Anything that gets in the way of that – even visually – could easily make me choose not to click. In this situation, RSS ads could get in the way – which means they’d lower the revenue earned by these sites.
But there is at least one big caveat here: offline reading. I’ve heard many, many reports from customers who really like FeedDemon’s offline reading mode, and I use this feature myself whenever I travel. Before getting on a plane, I’ll often tell FeedDemon to download all the latest items in my subsriptions, then when I’m on the plane I’ll put FeedDemon into offline mode and read everything that was retrieved. Others use FeedDemon for offline reading on subways and long commutes – basically, in any situation where there’s no internet connection available.
This is where summary feeds fail for a lot of people. If you post only excerpts and expect readers to click through to your site, you’re not serving those in your audience who wish to read your articles offline. RSS readers could pre-fetch links so that your web site is available to them offline, but when you consider the number of feeds many people read, that would involve an awful lot of unnecessary bandwidth consumption (not to mention space on your hard drive).
Perhaps one solution is to offer two feeds: one with excerpts but no ads, and one with the full articles and also ads. I’m not usually one to recommend having multiple feeds (quite frankly, I don’t understand why so many bloggers have separate links for RSS, Atom and RDF feeds), but in this situation it might make sense.