Yes there are some bad effects of greyness but there are also good ones.
Humans are social animals and in order for any society to work there needs to be compromise and, as mentioned earlier, moderation.
If we were all brutally honest about everything we would not be able to stand each other.
Good or bad greyness, I suspect, would be decided by intent rather than degree of shading.
One can also protect with "faint praise".
Glenn