Last time I traveled, I was randomly selected for further checks in Dublin, London and Paris... (with Sydney, Singapore for the connection and Manchester being the only places where I wasn't hassled on the voyage). It was a little irritating, but what annoyed me more was the attention from other passengers. If I'm complying with further instructions, smiling and being pretty good natured about the black parisian who wants to get friendly, the irish guys who want to paw through all my shit, or the guy with bad teeth who wants a feel as well, it doesn't really need to be a spectacle.
To be fair, the one in Paris was because the dick behind me set off the metal detector before I was through (walking through right behind me, despite the signs). The rest I guess were either because I had a laptop, or look too distinct to be a law abiding citizen (which makes no sense, because you'd think the trick would be to fit right in with everyone else).
Annoying, but that's paranoia for you. Not really worth a fuss seeing as it only delays everyone further, and probably worsens the situation for you. I just hope that they manage to get someone using that shit every now and then, to justify the irritation for everyone else.