I think the thumbnails I picked out in class were stronger, I'm too lazy to repeat what I said. Also the mouth with the figure inside it works when its zoomed in with the lips and the figure, including the nose puts in too much information. And you remember what I said about The Rolling Stones so that's my two cents.
Really great thumbnails. The loose approach with the washes and the energy of the scribbly pen lines go really well together. Add the strong contrast and they're like mini-finished images. Try adapting this on a larger scale.