Q: Or why do they look so dirty? I don't mean YOU, just "people" as a whole. Rainwriter, you have made a good point.
A: Maybe because they don't see them so they forget to wash them. I had a teacher once ask us all if we washed our knees. He told us about how he had been gardening in his shorts, then went in to take a shower. After he got out his wife asked him why he didn't wash his knees, because they were still pretty dirty. He told us that he never washed his knees. He just kind of washed the important parts and let the shower running the soapy water over his body clean the rest. So, maybe people just forget to actually clean their elbows. Or maybe it's because they constantly put their elbows on stuff. Mine are resting on my desk right now as I type, even though they shouldn't. If my desk is dirty, bam.. my elbows are going to get dirty.