Heh! This may be TMI, but walking over my untidy floors I use my bare
feet to feel and find small things that shouldn't be there, like
nails, pins, tiny nuts and bolts, tiny shards of glass or crockery,
and last but not least, the tail or paw of a cat :-) These are the
kinds of things that can hide in carpets and give trouble to vacuum
cleaners.

In order to avoid having to brush off my feet manually, I have the odd
bristly doormat in the internal doorways. I can use them to brush off
my feet as I pass.

Don't bet on it.
When I was a mailman there was one that somehow got into one of my
socks. With me walking 96 blocks five days a week it was at least two
or three inches into my foot before it became painful. When the doctor
pulled it out I asked him how could a hair possibly get into the foot.
He said the constant movement when I was walking had worked it up into
the skin and then it just kept going farther and farther until I
noticed the pain.

With your feet being so tough it would probably be more difficult for
a small piece of glass or a thumbtack to penetrate your foot than for
a hair to do so. After all, a hair is as thin as, well a hair, and
with it going into the skin from the very end instead of the root end
it is more likely to be as pointed as a very sharp needle.

Now since we have dogs and cats in the house I always run my socks
through my hands before putting them on and not only turn my shoes
upside down and give them a couple of raps before putting them on, but
also remove the insert from the shoes at least a couple of times a
week to make sure there isn't anything embedded in them.

Ah, for the days when I was a boy and only wore shoes on Sundays
during the summer months and thought nothing of it if I stepped on a
nail sticking out of a board unless it went deep, but also waded
through mud and manure every day when I drove the cows from pasture to
the barnyard. Who knows; maybe all that acid and other things in the
cow manure actually helped me to stay free from infections.