Sometimes you can look at something that's not there and upon NOT seeing anything, deduce useful information about the target of your observation.

Take this half-naked elf girl for example - you can't see her shirt, skirt, nor dress, because she's not wearing any, in fact she's not wearing anything covering her body from below her neck to above her thighs and that alone should give you more information about her, than any backstory you might fit in as many words as you've just read.