One that springs to mind is the Highwayman "nightclub" on the outskirts of Cheadle Staffordshire. Having spent many a shit night in that awful place in my youth me and my brother decided to check the place out after it had closed down. It had been closed for quite a while and was awaiting redevelopment and conversion into dwellings. We headed inside and enjoyed reminiscing as we wandered around the old shithole. Unknown to us someone was living upstairs. We were soon aware that we weren't alone and spent what seemed like ages hiding behind the bar in a space where a fridge or something had once sat while this person searched the place. I remember trying to think up reasons for why we were there and how to get back to our entrance point in the near pitch black boarded up building. A quick dash once the footsteps seemed to be far away and we were up and out over the sketchy broken corrugated plastic roff above the "indoor garden" area. TBH I think this is the only close call I've had. I usually spend hours working out the most covert way in to a place which usually results in a complicated awkward effort only to fand an open door or suchlike on my way out.