The last time I went to (imposter style, non-cart having) dim sum, I had duck gizzards in vinegar sauce. I did not like it but...I tried it!

And you are totally right about the cart location thing. I'm always on the hunt for the one with the coconut jello dessert thing, or the sticky rice with mushroom and sausage wrapped in a giant leaf. Or the elusive gailan cart. And they are always nowhere to be found :(((