Back in 1994 at Heathrow I got a patdown by a female security guard that I felt was excessive. She felt all around by breasts and I thought it was creepy. I had HUGE boobs at the time, so I chalked it up to maybe they were suspicious of what was actually in my bra. I felt it was ridiculous though.
Nowadays, especially in light of the incidents where explosives were likely smuggled on board by women, I think it is indeed neccessary in *some* cases. However, what a fine line to walk for guards who have to perform these searches. I'm sure in *most* cases they're just as uncomfortable about doing it, as the person is getting it. I certainly think that whenever possible, they have female guards search females. Males search males. Not always possible though.