What mechainc brings their tools out of the shop and into the bathroom with them? Maybe the crescent wrench was used in the bathroom to fix a dripping fixture or something.
I've also definitely gotten nearly that dirty before. If i don't degrime an engine before working on it, all that thick black built up grime will eventually end up on my hands and forearms. As i scratch myself or wipe sweat the grime slowly covers most of my body. I also often have to lay on the dirty shop floor or driveways which can also contribute to getting filthy.
To be fair, I've met some absent parents that genuinely don't care if they see their kids again, and unfortnately it is possible for someone like that to be capable of being an astronaut.