Some do some don't, some are easy to spot and others you won't realise are close by. I've paid a visit to a girl with a guy parked right in front of the house at 11.00 at night, he was obvious, and a couple where I was taken quickly upstairs with the downstairs room door firmly closed, but I could hear there was somebody there. You don't want to think about it too much, I've also met SPs who've either phoned or text somebody when I got there, probably uses that as a warning to any potential nut job that they'll be missed if they don't call back when the meeting is over.
