While the majority of blog readers might be willing to accept advertising when they visit blogs it is also a fact that many also run ad blockers that will strip the ads from the blog being read. It is a different matter though when it comes to RSS feeds as RSS clients don't currently incorporate any type of ad blocking. Due to this more and more blogs are adding advertising to their feeds as an additional way to monetize their work.
I am not against this happening as I do the same thing here (as you can tell when you read my feeds) but what I am seeing is that more and more ads of the banner type are showing up and on top of that they are getting increasingly larger. It is to the point that in some cases the ad is bigger than the actual content of the feed post. On top of this though these same sites aren't just happy polluting their RSS feeds with oversized ads but they are pushing reader tolerance even further by adding the typical sized banner ad as well. So you end up getting two ads and next to no content - talk about pushing your readers to the limit.
The real danger in this trend is two fold. One effect directly hurts the offending blog as pissed readers unsubscribe in growing numbers. Whether the number of unsubscribing readers will ever equal or pass the number of new readers subscribing is open to debate. It is a debate though that blog owners shouldn't even be having in the first place.
The second danger though is far more reaching in its effect as it could affect all blog publishers ability to add to their revenue stream via their RSS feeds. Just as browser users got fed up with excessive advertising and whose cries for help were answered by ad blocker software blog owners could find the same happening to RSS client software.
If there is one simple rule in the software world it is that if there is a need someone will write the code. So as RSS grows in popularity so will the number of readers who are getting sick of excessive advertising and it will be a short step to some author to be the first to include the ability to strip ads from the RSS feed. Once one program does it the rest will surely follow suit and all blog publishers will lose in the end.
It's too bad that greed trumps common sense and the majority pay for the excesses of the few.