this post is off-base. avril & katy are pretty much exactly what your average radiohead fan looks like. their actual, real fan base is overwhelmingly composed of attractive young females (and homosexual men). like tori. those dudes you see walking around talking about how much they like radiohead are in actuality just trying to get laid and are really into stuff like qotsa.
the songs are about identifying with the audience's experiences. if you actually studied it, you'd certainly see a very large overlap between radiohead and avril (katy perry, less so). they sell records to the same demographic of young, insecure women. it's just that avril is the happy side of it and radiohead is the dark side of it.
i sing radiohead when drunk all the time. planet telex, paranoid android, street spirit...
www.wewantinsanity.com/am2/publish/mikejohns/Name-DroppingRadiohead.shtml