there is so much that could have gone wrong here. he could have picked up bacteria from the handles or the tap. Don't reopen petri dishes once they grew bacteria as they release spores. It's best if you tested them from the same person as well. the way soap kills germs isn't so much from contact. its from physically scrubbing. And if he didn't scrub long enough not enough germs will be removed. The soap attaches to the germs and then gets washed away with water. alcohol penetrates the cell and breaks down the membrane. actually 60/70% is more effective at germ killing because it takes longer to dry giving it more time to do so! And vinegar disrupting the cell membrane as well and messing with the pH which causes cell death. Fun facts!
Those are to get smells (like garlic smell) out of your hand, NOT for cleaning your hand So it would have a lot of bacteria like swabbing bare unwashed hands
Also this doesn't show necessarily bacteria, petri dishes grow mould and fungus from spores so you need to have a blank dish as a control. I would stick to real proper controlled experiments rather than some muppet in their home
