Green’s Dictionary of Slang

1. typically German, esp. of recent immigrants who have yet to adapt to America and still retain their old-country crudities.

1862		A. Gray Letters (1893) 495: I was [...] copying out Grisebach’s manuscripts for the printer (for the printer won’t touch the Dutchy-looking thing) [DA].
1893		J.H. Ross in King’s Business 127: The faces are not ideal but Dutchy [DA].
1955		B. Appel Tough Guy [ebook] Billy Muhlen, the dutchie from the dutchie block on Thirty-Eighth Street.

2. low-class, dowdy, slovenly [SE Dutch].

1901		Monroe & Northup ‘College Words and Phrases’ in DN II:iii 139: dutchy, adj. 1. Slovenly; unkempt; the same as tacky. 2. Loud, of ill-matched colors.
1915		M.G. Hayden ‘Terms Of Disparagement’ in DN IV:iii 214: Dutchy, slovenly. ‘Those little kids always look so Dutchy’.

3. typically Dutch.

1947

N. Algren Neon Wilderness (1986) 148: I kind of liked hearin’ him talk in that slow Dutchy way.