''A lot of stars, in my opinion, don't appear as glamorous as they should at the Oscars,'' laments Fred Hayman, the show's fashion coordinator, seen here with his German shepherd, Chumley, and a model inside Hayman's Beverly Hills specialty store on posh Rodeo Drive. ''They don't give the public what a grand evening like this demands. I think they have an awesome obligation to be glamorous.'' Hayman aims to correct this problem. He has agreed to let the women attending and appearing in the Oscar show borrow or order the gowns he gets from the world's leading designers. For last year's do, Melanie Griffith, Jessica Lange, Elizabeth McGovern, and Dianne Wiest made the pilgrimage to Hayman's ritzy racks.