Carol, you've made Thumper way too grammatically correct. His actual words are "If you can't say somethin' nice then don't say nothin' at all" I actually use a little section from Bambi, including that part, in my intro psych. class when I teach about child development--Bambi develops in some very human ways and my students love identifying the concepts they are learning about in a Disney movie.
I do agree with you and everyone else that these things are said out of ignorance, not malice. But hey, if you can't gripe about them here to fellow sufferers, where CAN you gripe about them?
Nelie