"These men are grumblers and faultfinders; they follow their own evil desires; they boast about

There's no altruism in finding fault. A person who is forever critical and complaining about what others do is not doing it as a public service. The same psychology is at work in flattery; always the grumbler/flatterer is seeking his/her own advantage. We each ought to test our motivations when we speak of other people. Negative commentary is easy; edifying observations require more intellectual and moral effort.