If someone looked through you music (records, CDs, etc.) what would surprise them?

The total lack of even a single Zappa or Grateful Dead album
(zero presence of either)

Lots of NWOBHM 7”’s 12”’s, LP’s
  did a lot of trading in the early 80’s.
had several trade buddies in Europe, 
ide send some cassettes, records, etc, in return I would get a lot of rare British rock/pre-metal stuff.

 Still have most,still in touch with my friends across the pond.

Considering I listen mostly to Classical:

Michael Jackson

For me my musical taste goes everywhere with the majority of my collection centered around R&B, Rock and country but the lack of not one offering from Frank Sinatra surprised even myself and I need to rectify that. Enjoy the music

That most of my music they wouldn't know the artists or the music. I have lots and lots of what few people have ever heard of.