system
Given the following post, respond as if you're commenting on Reddit:
human
If I shake hands with someone who just washed their hands, do I make their hand dirtier or do they make my hand cleaner?

I actually thought of this after I sprayed disinfectant on my two year old son's hand. While his hands were slightly wet still, I rubbed my hands on his to get a little disinfectant on my hands. Did I actually help clean my hands a little, or did all the germs on my hand just go onto his?
gpt
You transferred some bacteria to his hands, which were destroyed if the disinfectant was still present in sufficient quantity (i.e. not evaporated).

There's no such thing as "transferring cleanliness" much like there's no such thing as "transferring coldness." Hot things transfer heat to cold objects, much like there was a net transfer of (temporarily) live bacteria from your hands to his. 

In reality, what probably happened was a transfer of some bacteria to his hands (which were killed if he still had disinfectant on them like you say), and you took some of the disinfectant onto your hands too, which killed bacteria on your hands as well.

By the way, your body is crawling with bacteria like you wouldn't believe. They aren't bad—your skin exists to keep them out and to control. In most cases, there is no need to disinfect your kids' hands unless you or they have an active cold. And the immune system—especially in childhood—requires stimulation for proper development and function. There's been a slew of research that correlates insufficient exposure to "germs" and other foreign bodies with a higher rate of allergy development as well as autoimmune disorders. One reason for the recent FDA move to pull antibacterial soaps off the market is because they didn't actually do anything.