I'm assuming from your post that you're African American. The "you don't look like you can sing" thing seems, to me, to be the flip side of the, "oh, hey, you're Black, I bet you CAN sing." Seriously, I've heard this. I'm multiracial, my father is Black and people, upon learning this have actually said this to me. They assume I can sing. I cannot. In fact, I couldn't carry a tune if you gave me a basket to put it in.
People are funny.
Loved your story.