The AVS forum thread is forever-long (currently 72+ pages), but on the page 52 in your link, we have this response from MrHiEndAudio (who apparently is or represents TUC) at post #1545 on p52 of the AVS thread:
" ... Bingo you mention Modwright. They do less work then we do and charge more.
ModWrong's end result does not measure as well as our work, nor does it sound as good. They are not A+ BBB rated. Last I checked they are not even endorsed by the BBB. ..."
To my mind, that saves me the trouble of reading any further. The BBB does not "endorse" ANYONE; to become a member of the BBB a firm agrees to a dispute resolution process, nothing more. Currently BBB members are referred to as "Accredited" which is the new term for "Member" (changed a couple of years ago).
Moreover, a consumer can enlist the BBB to mediate a dispute with any business, member or not, and expect the same process to be followed and the same level of impartiality to be observed. So, Modwright could just as easily and just as satisfactorily resolve a complaint between a consumer and the firm, via a BBB mediation, as TUC could.
The only times I ever see claims that a business is "endorsed" by the BBB are when said business is up to something, or is fighting a (usually well deserved) credibility problem.
BBB membership by a business for a consumer considering a prospective purchase or relationship has value, but only in terms of what it does when a problem arises (which are part of that business's BBB record), and how long that business has been a member. Months are useless info, Years are nice, Decades are the real deal. Zero complaints are not necessarily better than a reasonable number of well-resolved complaints; it's the unresolved complaints that matter, and even then the long term history is critical.
Furthermore, you do not need to be a BBB member business for them to have a record of issues on your company. They publish the same details on non-members as members; the only difference is they offer a search function where only BBB members will show up for consumers.
It's a trivial process to dissolve or quit the membership of one company and register another which carries on the same business under the same principals, once the sh*t becomes too high to get into the office door. The new company will, of course, have an unblemished BBB unresolved complaint record.
It's also not necessarily a problem if a business is not a BBB member. Many businesses simply don't need to be ... their customers can find them if necessary, and it may be a small community they operate in, for example.
The last time I had a retail business there was no BBB chapter available and even today (30+ years later) there is only one office, in a different city, within 500 miles of me (my location has a population of 230,000 with 400K within 60 miles).
Of course everyone is free to come to their own conclusions, but when i see the phrase "endorsed by the BBB" I run, not walk. BBB membership is nice, don't get me wrong, but it's not a badge to lure consumers with either.
EDIT: Didn't even notice it until I reviewed the post, but he refers to Modright as "Modwrong" as well (and this is just one post of a thread I'm not going to bother reading through ... hmmm).
I've been in business, in fact even the Audio business (many, many years ago) and I can tell you this is a huge "NEVER" in the ethical businessman's rulebook. NEVER cut down the competition. EVER.