Usually, I do not touch my cat unless it knows I'm right there,
otherwise I give it verbal notice before touching it. That
probably keeps them sharp sensory wise. Sudden contact probably
can be alarming/memorable.

Yeah, it depends on how intent they are, as Brandy?Alexandre put
it (funny, in my opinion):
"I'm wondering if you can really teach a cat "no."  I mean by "no"
that they have to stop what they're doing, shut up and sit down.
Kami responds to "no" as in "oh, okay, I don't really have to chew
the power cord," or "all right, it's not that important to me to
drink out of the shower faucet." But I was eating ice cream and
"no" had zero effect.  It meant absoluely nothing to her, as she
insisted on putting her face in my snack and trying to get some
for herself."

I dunno.  Oscar likes to watch me throw a little ball we have (not nerf, but
similar) ... if she's in the mood, she'll chase it, too, but I have to
retrieve it *sigh* ... and if DH bounces the ball off the wall (catching it
each time so that Oscar can't get it), Oscar can't seem to help but watch each
arc.

We haven't used it as a means of distracting her from something she wants to
do, though; these are just observations.