What do people think we’re listening to?

I was riding the bus today and an elderly gentlemen gave me a look. You know, one of those looks of disapproval, sort of how folks must have looked at teenagers in the 80s who had 80s hair or how people still look at folks with mohawks or weird piercings. He was giving me this look because I had my little ear-bud things for my mp3 player in their proper place and he must have been thinking I was listening to rap music or some such, because if he had actually known what I was listening to I doubt he would have given me that look.
After being given this look it made me wonder whether iPods/mp3 players have started a new trend of disapproval just like 80s hair or mohawks or weird pierces did. Millions of us use our mp3 players, whatever brand they may be, on a daily basis. They’ve shaped the way our society (speaking in the U.S. here) in ways people probably never though possible. How many of us can honestly say we knew right from the start that the mp3 would replace the CD? It has, even though they’re still making CDs (which poses some serious problems for the future of the music industry when the mp3 officially takes over and CD stores go out of business).
Getting back to the point, do we hold any sort of bias towards iPod/etc. users? Do we automatically think, upon seeing some teenage kid or college-age man with headphones and an iPod, that such a person is only listening to music, and most specifically poppy musical garbage that hasn’t technically done anything to advance music as an art? Or maybe we think they’re listening to their indie bands, sucking up all their silly folk music about saving the planet and what not?
For the record, I wasn’t listening to music. I was actually listening to a podcast interview with a fantasy author, and a good one at that. In fact, I listen to a lot of podcasts and audio interviews, and other such things (even listened to a few lectures on there). Sure, a lot of folks probably only listen to music, but that’s not all of us. Some of us even listen to music that older folks might think is quite acceptible (classical music, for example).
What do you think? Do you have this sort of bias when you see people with ear buds? Do you think this is a common thing among people in general? Do people scoff at the iPod/mp3 player fad in the same way people once scoffed at rock music?