Medical procedures are not intended to be fun and are not approached that way. The recipient of a medical sounding most likely needs the procedure to open a narrowed passage and there is the expectation of tissue damage and pain as a result, either at the time or afterwards.
As a result, I think comparing sounding for pleasure to the medical procedure is like comparing anal sex to a colonoscopy.
Sounding does not intrigue me. It seems like it would be painful. I have passed urethral catheters and it has been painful and that does color my interest. On the other hand, if Mr. Navarro were interested in allowing me to place a sound into him with his guidance, it is conceivable that his pleasure might trigger a willingness of my part to have it done to me.
If I ever did try this, I might consider an antibiotic afterwards, at least for the first time,