You can say anything you want to about anybody, as long as you add bless his/her heart to the end of it.
"That baby's uglier than a buck naked blue jay, bless his heart. He caint help what he is".
" 'at ol' gal's dumber 'n mud. Her daddy's porch light flickered a bit too, if'n you catch muh drift. Bless her pore little heart, she caint help what she is."