This whole drawing is worth it just for the line of his lower lip. That's a good line. It's just the right thickness at the bottom, with just the right amount of tapering as it goes up into the light, and just the right distance from the mustache before it fades off to white. That one line is a thousand times better than the entirety of that djinn drawing from yesterday.
Yes, this is the kind of thing I look at in my own work. Sometimes just that one line can make it all worthwhile.