I think JanN makes a good point.There is always the risk that friends or family will crucify a competitor unfairly,or a disgruntled or fired employee might start a negative thread....and I've seen that happen more than once.
As an operator,I've had some unflattering posts,but some of them were justified and I was able to act on them.I might not have known otherwise and ,while it hurts to get beat up,they can be helpful.
Anyway,I vote to let it rip and let intelligent people decide for themselves.
I also think it's fair for forum members to question the authenticity of critcal or overly glowing posts........ seem to remember that Don once caught a member with multiple screen names making lots of posts praising himself.