It seems a lot of Yahoo! Pipes are not working properly. Either the sample results are not there, or there are some HTTP errors. It seems there is no any voting feature or anything that indicates stability of the pipes.
There is an option to Report abusive Pipe, but is there any option to report broken/non-working pipe?
So either author will be notified or other people would be informed and choose only these, which are working. Even access to any comments or reviews would be helpful.