Both Dave Walker and Tim Bray state their aggregators of choice barfed when trying to read a post entitled </TAG> because their aggregators of choice didn't know how to deal with tags in content. Weird. RSS Bandit dealt with it fine. Screenshot below.
Combining this with Arve Bersvendsen's comments from yesterday I suspect that the main problems that people complain about when processing RSS is due to sloppy programming. I am amused that Tim Bray thinks adding a lot more complexity is the solution to the problem. I guess that's why I don't work on standards bodies. :)