Just read this on the online column. Not advice from her, but one of her readers from Oregon.
On when to offer "constructive criticism":
Two of the wisest women in my life have shared some advice with me that has served me in good stead. My mother told me that if it can't be fixed in five minutes, with the materials at hand, then don't mention it. So, an unzipped zipper, doughnut crumbs on your shirt, parsley in your teeth -- all fair game to bring to someone's attention. Height, weight, stain on clothing, size of nose -- off limits.
The second piece of advice was given to me by a dear friend, about how to tell if one is gossiping or not. If I'm not part of the problem and/or I'm not part of the solution, then there is no need for me to discuss it with anyone. These two guidelines have been invaluable to me and I've taught them to my kids from the time they could comprehend them.
Shelly in Oregon