Maybe it’s biochemical…what’s biochemical mean again?

Now that I’ve come clean about my snarling contempt for SUV drivers, I thought I’d be upfront about another little quirk I’ve been keeping secret: I’m invisible.
And I don’t mean metaphorically. I obviously don’t mean literally. I mean biochemically. Actually, I don’t know if that’s what I mean because I don’t quite understand the definition of biochemical.
Here’s the deal: You know those automatic doors in supermarkets and other large stores? They are activated by people walking up to them? They are convenient when carrying large loads or when the effort of just opening a door is too much? (They are, of course, quite necessary if one is disabled).
I don’t activate them. Like, 80 percent of the time they just don’t open.
Now when I first noticed this happening, I assumed they were all just broken. That might seem unlikely but I do live, after all, in a city where as best I can tell no one has replaced the receipt paper at any of the gas station pumps since 1998.
But it soon became clear, it’s not them, it’s me. Because if I sit and wait for someone else to come along, the door will open for them and I can sneak in.
This situation is not isolated to automatic doors; I often find that the body-activated hand-dryers and towel dispensers neither blow nor dispense when I put my hands under them. I can, usually, get them to work by punching them or occasionally leaning both hands on them with my entire weight. Not sure how this looks to others; probably better than me wiping my hands on my pants.
I’m also unsure if this relates to an incident some years ago in which my ex gave me a watch, as a gift, which promptly stopped ticking. Two replacement watches later, the watch salesman gently informed me I might be “one of those people who can’t wear watches.”
Unclear what kind of people that is.