unfashionable,
unstylish not in accord with or not following current fashion; "unfashionable clothes"; "melodrama of a now unfashionable kind"
dowdy -
lacking in smartness or taste; "a dowdy grey outfit"; "a clean and sunny but completely dowdy room"
styleless,
unstylish lacking in style or elegance; "a styleless way of dressing"; "expensive but styleless country tweeds"; "wearing unstylish clothes"