Accuracy certainly is in the mix because these speakers sound about as real as a speaker can reasonably get. Because of that I think they walk a fine line and when people get an unfavorable impression of them i think they have not be set up well. I have never found them to be bright, lean, fat, tubby, warm, cold. They are about as spot on in the middle for me as a speaker can get.I completely agree. None of the Thiels I've heard (CS7.2, 3.7, 2.4, 1.6) sounded overly bright or cool to my ears (altho' the CS1.6 could be strident at high SPLs with certain female vocalists, I think this is related to the distortion at 1 KHz seen in soundstage's measurements).
Shane Buettner's review of the CS2.4 opined that the midrange had a "slightly-on-the-cool-side-of-neutral sound" compared his reference Vandersteens. But I've also heard the Vandersteen 7 (which is a SOTA-level speaker, IMO), 3A Sig, Treo, Quattro, and I lived with the 2Ce Sig II for 10 years. I have no idea what he meant. To my ears, the Thiel CS2.4SE sounds very neutral, resolved, open, and transparent through the midband. In fact, it sounds superbly balanced at all frequencies. When I listen to performers that I've seen live, I have no trouble whatsoever imagining that they are in front of me.
My conclusion is that people complaining about poor SQ from Thiels have only heard them poorly set-up or with poor-performing amps and/or sources.