i think the actual effectiveness of sniffer dogs is over estimated, i recently was confronted by a snifferdog on a bus from amsterdam to zurich, i had a grinder that had been used to 'mull up about 3 ounces of potent weed, it was full of resin and thc powder, this was in my hand luggage that the dog sniffed and said dog was unable to detect it.
they are used as more of a mental deterant, if u have to walk past a sniffer dog with 5 or so pills (not a dealer, just a personal dose) if u are not used to the police or "good at keeping ur cool" and start to freak out then thats wen most people imo get caught.
i also agree that police at events generally dont have a positive influance, why not have pill testing or more medical staffing/chill out areas, i think these would be far more effective at minimising the health risk to the punters who choose to take illigal drugs
just my 2cents