to profile or not to profile?

Former Met police chief Lord Stevens says he should be fasttracked onto his flight because he doesn't fit the profile of a suicide bomber. Yet, some of the suspects currently in custody don't "fit the profile" (from the home counties, related to Tory activists etc).
The storm about profiling has again raised its head, but profiling has been taking place for quite a while: Customs & Excise regular use it (if you arrive at the same time as a flight from the carribean, or asian sub-continent then nearly all the C&E chaps are looking at people coming off those flights, once I had to hang around in the red channel waiting to pay some duty and the C&E people only came out of their back offices when these flights came in). I believe they can justify profiling on the "output" side, as it is looking at whole flights, and particular types of people (solo travellers etc), rather than on ethnic or religious grounds.
But profiling on the input side (ie prior to flying) wont work because, to use Lord Stevens argument for it, the terrorists will manipulate the "rules" and shave their beards and look like respectable old business travellers with suits, shirts and ties (and will probably get an upgrade...:)
Meanwhile, the Government needs to tell us why they are doing various things (like reducing the size of handluggage), rather than saying "because we say so".