I also wanted to mention that shop owners will often run subs in undersized or improperly tuned enclosures. Even a lower grade woofer (for pro, home or car design) can made to be sound okay if put in the right box. A lot of enclosures for subs sold on the cheapy, 'teen' market are placed in improperly tuned or undersized enclosures, so it's not always the manufactuers fault, either.

Adam