Hi.
(1) I too have been to Woodsyi's house several times and heard his system. It is one of the best sounding systems I have ever heard. Great imaging, a 3D soundstage, great clarity, detail and tight bass slam and control. I can assure you that the racks have no adverse impact on imaging and the sound of the system.
(2) I had a very respected home audio engineering company (Rives Audio) design an acoustic treatment package for my family/listening room. Part of the design was to place floor to ceiling book racks along the read wall to absorb, difuse, and scatter sound waves to reduce the reverberation and reflection off the rear wall back to the listening position. The rest of the package included absorption panels RPG B.A.D. panels, low frequency traps in the corners behind the speakers and 1/2 round plywood on each side of my wall mounted plasma TV for dispersion off the front wall.
(3) In most rooms one must somehow tame the reflections off the back wall with a combination of absorption and diffusion. There are photos in my gallery.
Laura
(1) I never criticized whoever's sound system sound bad at all. Just without any tall structures inside the listening area will make it sound even better.
This is physics. Less UNcontrolled soundwaves deflection better will be the sound.
FYI, my audio den is in the basement, some 1,000 sq. feet area. Yet I make sure there is NO tall structures, e.g. tall records storage racks, in my listening area. I don't allow any thing placed btween my sweet spot & the loudspeakers, not even a lowly coffee table which is again a very common acoustical BOOBOO committed by many many audiophiles.
I have my audio racks fully covered with sound absorbing blankets al ALL time.
(2) An acoutical consultant hired by a leading American electrostatic/hybrid loudspeaker manufacturer commented that he could detect the sound difference when an additional loudspeakers are placed next to the existing pair of loudspeakers. He does not recommend anything redundant placed inside the listening room. So go figure!
(3) The rear wall is a crucial reflective surface for the frontal soundwaves emitted by the loudspeakers. So it should be kept any clear out as possible.
Tall records storage racks will cause UNcontrolled soundwave reflections or "diffusions". I'd not do it nor recommend to any audiophiles.
c-J