As most members know, I'm into some really extreme sexplay, but sounding just gives me the willies. It's like pushing a knitting or crochet needle into your urethra: no thanks.
I have played with two guys who really really liked sounds; once was many years ago (30 now, to be exact
) who wanted me to insert as much of my pinky into his dick as I could, and made it to the second knuckle. The second brought an actual sounding "kit", and his thing (among many) was to have me masticate (hard) his dick with a sound inserted. In each case, it was a question of doing something otherwise distasteful to accommodate someone's odd request.
The concept of either sounds or catheterization is deeply disturbing to me at a base and fundamental level: it's neither something I wish to repeat for others nor anything I can possibly imagine for myself. I get a reflexive pull on my hips just thinking about it.
To the member who worried about glass: it's the most easily sterilized of any material, which is why it's used. Metals or plastics can accumulate bacteria more easily. This is an explanation, not a recommendation.
IRL, sounding is exceptionally rare compared to more mundane extremities like WS or fisting.