Your implication that QVC deletes critical posts is simply incorrect. We see critical posts all the time -- many dealing with hosts' presentation styles. Posts and threads are eliminated because of violations of the board stands -- standards which all users must agree to in order to participate; unfortunately, many people are unable to act like adults, and this is why we see threads disappear.
In regards to our opinions, yes, I am sure QVC has an interest; however, bear in mind the only opinion that matters in the end is money. While a tiny percentage of participants on QVC's forums may complain about something, when thousands upon thousands of others are spending money and purchasing items during these supposedly awful presentations, whose opinions really matter.