And whilst we're on the subject, here's my $0.02. I once trod in some proper mustard dogshit on the way to meet a girlfriend. She just had to invite me in to meet her parents, didn't she?
Option 1 - make excuses to remain outside.
Option 2 - take shoes off and leave them outside, and risk having perceived mental age of five.
Option 3 - come in, and hope for the best. I chose 3.
Another story, when I were a sixth form student I made some extra £££ cleaning at Sun Alliance. It's a massive company with a massive office, and several different toilets. The cleaners often recounted the legend of the Phantom Shitter, a mystery character, presumably a pissed-off office worker, who would shit in bizarre places such as plant pots and behind curtains. The phenomenon stopped one day as suddenly as it started.