The last three times I went to the UK with my wife, see is Mexican and could be mistaken for Arab, the authorities gave her extra scrutiny and none for myself. The agents were courteous and respectful and the delay was just a few minutes.
The last time we went to Spain, customs singled me out and waved my wife through.
This is all about safety and so long as it is done with respect and courtesy I have no problem with it. The TSA is a whole different subject.
Relative to the TSA I had a very fine bottle of Single Malt Whiskey in my luggage. My luggage made it but my bottle of single malt was gone. The next time I traveled I put a note in my luggage that said, “You assholes stole my last bottle of single malt, please do not steal this one.” My bottle of fine single malt made it to destination.