2) More food in the floor. If the food is smashed as if by tiny stomping feet, the presence of a toddler is very likely.
3) Even more food. Especially under the table as if flung from great heights.
4) You find important things hidden in odd places long after you’ve been forced to replace them.
5) Odd sightings of what looks like once-worn pants with still snapped diaper inside. Owner absent. This is exactly as I found it.
6) Occasional blurs of naked butt.
If you are able to capture the 15 month old, my recommendation is to not let go. Even when you’re very tired from sweeping up food all day.
And perhaps, retrieve the diaper and put it back on.