[ccvannorman]

I have always felt like I would appreciate candor in people talking to me about my business. But every time I have offered constructive criticism it has not benefited me. So I stopped doing it.

Not sure what the solution is, but I feel like building a culture around "best ideas win" and rewarding the process of coming up with improvements and implementing them could be good. You could seed this at first with improvements you were already trying, but when people see "Hey, Joe Schmoe came up with this great idea and now we do it" would be a boon to your improvement culture.