It is a touch annoying when you get pulled to one side when you've doing nothing wrong though. No big deal, but there were disapproving looks and shakes of the head from people walking past. Felt compelled to tell them I'd only had a few pints of Guinness, but not sure they'd have believed me. I did lose my house key during the search as well when I loaded all my crap on the table, but no drama.
I've got no issue with it tbh. If you've nothing to hide and all that. It is the first time I've seen it though. I've seen sniffer dogs at big events, but they're usually for anti-terror as far as I know, although I am sure it's different at music festivals etc. If they are going to do it, they need to stop using apprentice dogs though and bring out the seasoned pros, and also try to ensure it doesn't result in bottlenecks which some have said was a problem.