“Politicians: Scrape shit from boots before entering” is a jocular sign that has been printed on many images.
 
“Another sign says: ‘Politicians: Please scrape shit from boots before entering’” was printed in The Daily Advertiser (Lafayette, LA) on April 18, 1997. Similar signs are for cowboys instead of politicians.
 
   
Newspapers.com
18 April 1997, The Daily Advertiser (Lafayette, LA), “Dining with Wolf” by Robert S. Wolf, Weekend! sec., pg. 5, col. 1:
Another sign says: “Politicians: Please scrape shit from boots before entering.”
 
Twitter
aaron w
@aw0L
http://twitpic.com/uowy - Politicians scrape shit from boots before entering
4:22 PM · Dec 20, 2008
   
Twitter
Rusty Redenbacher
@rustymk2
‘Politicians, please scrape shit from boots before entering.”  “This table reserved for staff “ONLY”. Thank http://instagr.am/p/Kg2qaomzDU/
12:36 AM · May 12, 2012
   
Twitter
Patricia Patterson
@ppatt17
Politicians: please scrape shit from boots before entering
Políticos: por favor raspen la mierda de sus botas… http://fb.me/IsYVyZSP
8:02 PM · Feb 22, 2013
   
Google Books
A New Leaf:
The End of Cannabis Prohibition
By Alyson Martin and Nushin Rashidian
New York, NY: The New Press
2014
Pg. ?:
In the corner of his spacious office, a sign read, “Politicians! Scrape shit from boots before entering.”
   
Twitter
Barry Dahl
@barrydahl
...and for the record, I lived in Arizona for 8 years. I LOVE the state, but not so much the politics.
@AZGOP
- but it’s a dry hate!
(The following text is shown on a sign.—ed.)
POLITICIANS
SCRAPE SHIT FROM
BOOTS BEFORE ENTERING
12:50 PM · Jan 26, 2021
 
Twitter
AMERICAN BADASS 🇺🇲
@SWFLPatriot
Great Sign!!
(The following text is shown on a sign.—ed.)
POLITICIANS
SCRAPE SHIT FROM
BOOTS BEFORE ENTERING
12:25 PM · Jan 26, 2023