The choices are: tip the cat's ear, repeatedly trap and anesthetize the cat
to check for a spay scar or feel the balls.  Yes, you have to knock out a
feral cat to check for these things.  Or trap the cat repeatedly to check
for a tattoo.  Both of the last two choices involve repeatedly stressing out
the cat.  Do you have any research of ear tipping causing harm to cats?
Which is better for the cat?

The tipped ear signals the cat is neutered *whether or not it is
trapped*.

A TTVNR program is not going to spend money, time, energy and resources
transporting a cat, having it sedated and paying a vet to determine if
it has been neutered, if they can help it.  The only way to determine
if the cat's already been TTVNR'd is to have some external visual cue.
The tipped ear is the UNIVERSAL cue to anyone who works in pet rescue -
vets, shelters, those who run feral colonies, people who do TTVNR. No
matter where that cat ends up, the ear tells people it's a neutered
cat.  A tipped-eared cat in a trap is released immediately so the
resources can be used to focus on cats who need the service.

Um, yes, it is.  What other *easily seen* visual cue do you suggest?
It has to be easy to see on a trapped cat that is constantly moving,
snarling, growling, lunging, hissing, swatting and trying to bite.  It
has to be seen at a distance when one is looking to trap a single stray
for TTVNR.  I wish there was some way to permanently dye the ear, but
there isn't.

,

You can't usually see a tatoo, especially at a distance. Most cats have
to have their ears shaved to see a tatoo.  Tatoos don't work on
dark-skinned cats.  Tatoos cost money to do, tipping is free.  Tipping
works well on all cats.

If there was a way to do it without tipping the ear, it would be done.

Seriously, and I don't mean this snarkily - spend some major time at a
local shelter.  You will better  understand why things are done the way
they are in animal rescue.  It is a process and experience that will
change your life forever - in so many ways.

WRT "the way things are done" at shelters -  the "returning the cat to
the shelter" recommendation isn't merely for the benefit of the hapless
adoptor - it benefits the cat, it benefits the shelter.  More often
than not, cats who end up with people like Phillip end up being dumped
- and being dumped is a FAR worse fate that being euthanized.  When one
returns a cat, it tells a GOOD shelter not to adopt another cat to this
person (I understand that the OC shelter did - fie on them!) and in the
process, a GOOD shelter will cousel the person about what went wrong,
hopefully making sure it doesn't happen again. They will also assess
their screning process and try to determine where they went wrong in
placing the cat in the first place.   In every shelter I have worked
at, returned animals get special consideration for time on death row.
So, you see, it isn't just a black-and-white issue.  Some fates are
worse than being euthanized, and education is the ultime goal of the
process.  In an ideal world, people like Phillip would work with the
animal - do whatever it takes to make the situation work, for life.
But people (in general) aren't like that - it is the rare person who
commits to an animal for life.  Shelters realize this, and that's why
they make the recommendations they do.  Animals in this society are
seen as disposable - and it's sickening.  And the shelters have to work
the system in such a way to try to educate people to think differently
about animals.  The only way to do that is to get people like Phillip
back in the door.

I hope you will take this post in the light it was offered - no
animosity, no flames.

-L.