It's maybe not the security staff at all, but the rules & regs that they are told to adopt by the Department for Transport. At my airport (BAA) I have a good relationship with most of the staff at the security post I have to use, they are very professional and stick to the rules AS THEY SHOULD, the only time I see them getting frustrated is when numpties who don't bother to read all the signage before the machines spend ages taking off their jackets, getting out mobiles and loose change etc etc for which they should have been prepared for!!
Most of them are absolute losers with nothing better to do than harass us (Pilots & employees) who have already been extensively screened and are just there to do our job.
If you make them out to be loosers, then that's probably why you get such a hard time passing through!! Why mock them for doing their job??? (and who extensively screens you before you go through security
)