
“Politicians are like diapers: they should be changed often, and for the same reason”
Not found in Twain's works.
A 1993 newspaper humor column attributes this saying to Reader's Digest: "Picking it up from a Reader's Digest fan, Willie, our ex-shoe shine boy, says some politicians are like diapers. They both need changed often ... and for the same reason."
Also attributed to Reader's Digest in Naomi Judd's 1993 book Love Can Build a Bridge https://books.google.com/books?id=AMmrqZkq3JQC&pg=PA262&dq=%22politicians+are+like+diapers%22&hl=en&sa=X&ved=0ahUKEwiQ2obup6LKAhUBS2MKHfacCmsQ6AEIITAB#v=onepage&q=%22politicians%20are%20like%20diapers%22&f=false: 'A quip I once saw in Reader's Digest said: "Most politicians are like diapers: they should be changed often, and for the same reason!"'.
Not found attributed to Twain until 2010 https://books.google.com/books?id=gNwqfJkXjVsC&pg=PA448&dq=%22politicians+are+like+diapers%22+twain&hl=en&sa=X&ved=0ahUKEwjUq_C6qaLKAhVM7GMKHTuwAfIQ6AEIIzAB#v=onepage&q=%22politicians%20are%20like%20diapers%22%20twain&f=false
Misattributed
Variant: Politicians and diapers must be changed often, and for the same reason
Source: Bill Hastings, "Books, Bricks, Nap's, Tom, , Tres, Tracy ..." https://www.newspapers.com/newspage/14184165/, Indiana Gazette, 1993-09-10, p. 11