Folks:
There is a unique situation where the "walking away from the table" technique actually WORKS. It may not be "professional," but the scenario I'm about to describe may be cause to do this.
This has happened to me. Let's say you're playing in league. It's your opponent's turn at the table. He/she is playing extremely, u-n-g-o-d-l-y s-l-o-w -- knowingly using the technique as a sharking method. Taking excessive casual walks around the table, feigning sighting angles on every single ball on the table, getting down on a shot, stroking a few times, getting back up, feigning sighting other shots, getting down on the same (or another) shot, popping back up, etc. -- over and over. By now, you're sitting in your seat, seething at the obvious sharking attempt.
This has actually happened to me. What I did, was to overtly appoint one of my teammates (the team captain, actually) to watch my opponent's turn at the table, and I would just excuse myself and leave. No need to sit there, and participate in my opponent's "low and slow" method of sharking. Of course, my opponent is well aware that I've left the area, with an appointed "watchman." I'd found this was a *great* way to not only avoid the frustration of being the target of this type of sharking, but it's also a way of getting back at my opponent -- he/she now knows the sharking cannot possibly affect me, BECAUSE I'M NOT THERE TO BE AFFECTED BY IT. Then, when it's my turn at the table, my appointed "watchman" signals to me (TXT message on cell phone, etc.) that it's my turn and I show up promptly.
This is about the only scenario (besides the aforementioned emergency bio-breaks, of course) where this behavior might be called for.
What think ye, folks?
-Sean