This varies IME. I had a polite yet firm screener at T2 recently, despite my being somewhat jetlagged-grumpy about confiscation of an unopened mini-wine-bottle from my previous flight (the UK is the only place that forces everyone into transfer security, I was coming from Canada on this occasion).

I do have much worse memories of T5 consistently being bad, more so in transfer security. The budget airports (stansted, luton and the like) are also quite noisy and grumpy.

I do find ZRH rather polite (it's done by the local police, who also conduct border processing). They will calmly double-check that you've removed your laptop, and will give you an assessment of shoes/belts if requested (I've flown in hiking boots before, plus my belt has issues in the WTMD). They'll even explain that you can take your swiss-army knife through, but that you should probably check it when returning since other countries might not permit it in carry-ons.