depressing in character or appearance; "drove through dingy streets"; "the dismal prison twilight"- Charles Dickens; "drab old buildings"; "a dreary mining town"; "gloomy tenements"; "sorry routine that follows on the heels of death"- B
A dingy building or place is rather dark and depressing, and perhaps dirty. Shaw took me to his rather dingy office
Dingy clothes, curtains, or furnishings look dirty or dull. wallpaper with stripes of dingy yellow. dark, dirty, and in bad condition (Perhaps from dungy (15-19 centuries), from dung)