I should keep several valve caps in my seat bag, so I can throw one away whenever someone is looking. Maybe a few kickstands too.
Granted, I've gotten pretty quick at dealing with all kinds of front wheel attachments. Some of my bikes have nutted axles. I figure that I've already got a little wrench in my bag thanks to the gear hub, and even the wrench isn't really inconvenient.
I have one of the bikes that was made with a dropout fork and disc brake. Sure enough the wheel did pull out at one point. That wheel now has a solid front axle and track nuts, and hasn't budged.
When I was in middle school, one summer, it suddenly became utterly anathema to have any kind of attachments on your bike. I don't know if it was because some "cool" kid came through with a stripped down bike, or what. Anyway, within the space of a couple hours, all of the kids had gathered in my backyard, and we were stripping everything off our bikes: Fenders, chainguards, kickstands, everything. I don't think it occurred to us that we should remove the valve caps, or those were already gone. All of that stuff ended up our shed, and my dad probably threw it all away eventually.
Of course it was impossible to remove a Schwinn kickstand. Whoever tried to do so ended up worse off, with a dangling kickstand that had to be held up with a piece of hockey stick tape.
My "cool" days are over, if they ever began. Still, something reminds me of those days, once in a while.