Green’s Dictionary of Slang

a second-rate dandy.

1864		Hotten Sl. Dict. 178: Weak young men who keep bull-dogs, and dress in a ‘loud’ stable style, from a belief that it is very becoming, are sometimes called mild bloaters.
1870		Hotten Sl. Dict.
1890–1904		Farmer & Henley Sl. and Its Analogues.