ROCK DRESS CODE: Feeling left out? We certainly were when Mr. Blackwell announced his infamous Worst Dressed list last week. The relentlessly self-promoting designer chose film actresses, TV stars, even Sarah Ferguson--but no rock performers (the only close call being Barbra Streisand, but it's probably a stretch to consider her anything less than a multimedia threat). Never fear. Maybe (Blackwell winners) Meryl Streep and Vanna White shop at the same garage sales as David Lee Roth or Nick Rhodes. Who do you think are the worst-dressed rock stars--and why? Send your rock-bottom 10, with brief (that's brief) comments to Pop Eye, Los Angeles Times, Times Mirror Square, Los Angeles 90053. We'll print the winners next month.