When directly asking for criticism I'm tempted to declare "I will look butthurt at first but keep going and later I'll be thankful for learning so much more."

My usual version of this is "I don't like receiving criticism, and I don't promise to take it well, though I promise to make my best efforts to do so and I usually succeed. That said, still less do I like having earned criticism withheld from me, so my preference is to receive criticism where I've earned it. If you remind me of this, I will do my best to be grateful."