Er... I love Mark Twain but... African Gray parrots blush when angry or embarrassed. It's easy to see because part of their facial skin is naked or nearly so. The skin is normally a lovely pearly gray to silvery white. They can turn quite dark pink when feeling emotional. They also bruise easily there.

And for your self-esteem support, I know this isn't much but I laugh more at your writing than anyone else's on LJ and when I see your "by line" I think, Oh, goody! and bypass other's posts so as to get to yours first. And it's not just because of the laugh-inducing adventures, which are nearly always at your expense, but the literacy of your writing. That is so stupidly rare these days it's worth the mention.