“Between pigeons and politicians, it’s hard to keep the courthouse clean” is a jocular one-line saying. “Two reasons it is difficult to keep a courthouse clean” pigeons and politicians,” from “Lou’s News” by Lou Erickson, was printed in the Atlanta (GA) Journal-Constitution on September 21, 1969.
 
     
21 September 1969, Atlanta (GA) Journal-Constitution, “Lou’s News” by Lou Erickson, pg. 16-A, col. 3:
Two reasons it is difficult to keep a courthouse clean” pigeons and politicians.
 
7 October 1969, Charleston (WV) Gazette, “The Gazetteer” by James Dent, pg. 13, col. 1:
Fellow says he heard a couple of fellows talking about how dirty the Kanawha County Courthouse looked and one of them said, “Well, it’s hard to keep a courthouse clean with all the pigeons and politicians hanging around.”
 
20 May 1971, The Register (Danville, VA), pg. 8-D classified ad:
King Cole Sez:
Between the pigeons and the politicians, it’s hard to keep the courthouse clean.
COLE FURNITURE CO.
 
30 October 1972, Augusta (GA) Chronicle, “Broad View,” pg. 1, col. 1:
And the Augusta Optimist bulletin observes that “between the pigeons and the politicians, it’s hard to keep the courthouse clean.”
 
Google Books
20,000 Quips & Quotes
By Evan Esar
New York, NY: Barnes & Noble Books
1995, ©1968
Pg. 186:
The two chief reasons why it’s hard to keep a courthouse clean are pigeons and politicians.
     
Norfolk (NE) Daily News 
Reading the Comics
Merlin Wright | Posted Apr 2, 2007
(...)
Truly we live in a great country. Between the pigeons and the politicians, it’s hard to keep the courthouse clean.
 
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Pati Lara
‏@pati_lara
Between pigeons and politicians, it’s hard to keep the courthouse clean. — Unknown #quote
10:56 AM - 23 Nov 2011
 
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J. Darryn Zewalk
‏@darrynzewalk
Between pigeons and politicians, it’s hard to keep the courthouse clean. — Unknown
12:24 PM - 16 Jan 2012