I would say that if they are professional enough to get that far, they are professional enough not to be heard. They could be smelled though. They could also miscalculate how many rubbers to bring and run out.
Took this up, because it's got great dramatic potential. Start of it is here. (No sex scene yet; wait 'til it's edited and published.) I moved the historical era and the setting to something a bit different, but I kept the idea, so heck, if that works, it works. (I happen to know a good deal about the priest-holes in Tudor houses, having written a work on their primary builder, so it seemed like a logical relocation.)