My cats have always been indoor/outdoor when I lived where
it was possible (with a cat flap so they could come and go
at will).  The debate goes on, but a great many authorities
seem to feel it's better for the cat than being totally
indoors.  (Dogs at least get walked, and can be allowed out
in a fenced yard - without worrying about them climbing the
fence.)

Sophie was the same as your cats but Sweep was more determined and
although she was in while we were at work and at night she was sometimes
out when we were out. She was much more street wise that Sophie.

Judith

Forgot to say that Sophie did come home smelling of perfume one day, but
she was a very popular and cuddly cat.

Judith

I wonder if it was kool-aid

I guess I'm thinking it was something kids would do.  Food color...or
red kool-aid...would make the cat's fur pink without getting matted or
sticky.  Could  have happened when kitty was making his "rounds".  Has
anyone seen that big, coffee table sized book called Why Paint Cats?
Some of the photagraphy is frankly incredible, but disturbing in a way
as they practiced on kitty corpses.

PatM

I would think this is extremely unlikely.  Here in the UK, it is expected
that cats will wander around freely and it isn't seen as trespassing.  By
law here, a cat owner is not seen as responsible for what their cat does as
they are recognised "as having a propensity to wander" or words such as this
IIRC.  Therefore they cannot "trespass."
It's a different law for dogs, because they can be - and should be -
trained.
It must mean that we recognise in law here that a cat will just do as it
wants!
The only time I would worry that my cats might be in danger from neighbours
is if I had a pigeon fancier living nearby and my cat/s were tormenting his
loft by entering it, or hanging around on a regular basis and preventing the
birds coming down into the loft to be timed in after a race.

Tweed