Bum Steer

A “steer” is a piece of advice (cited from at least 1899, probably from Texas). Not long after that, a “bum steer” came to mean a bad piece of advice.
 
“Bum rap” is a related term.
 
   
(Oxford English Dictionary) 
steer, n.
slang (orig. U.S.).
A piece of advice or information; a tip, a lead.
1899 C. H. HOYT Texas Steer (typescript) IV. 21 You’re going back to Texas to give the voters of my district a steer. What’s that steer to be?
 
(Oxford English Dictionary)
bum, a.
slang
Of poor, wretched, or miserable quality; spec. bum steer, false or poor information or advice.
1859 in Pacific N.W. Quart. (1940) XXXI. 292 Bum River Ferry.
1888 Nation (N.Y.) 31 May 439/2 One of them..heard B. called a ‘bum actor’.
1896 ADE Artie xii. 109 He didn’t have a sou markee except what was tied up in a bum little grocery store.
1911 H. QUICK Yellowstone N. vii. 190 A stranger that had seen better days and had a bum lung.
1924 G. C. HENDERSON Keys to Crookdom 399 Bum steer, poor advice.
   
25 October 1901, Daily Iowa State Press (Iowa City, Iowa), pg. 8, col. 5:   
The Chicago Chronicle’s editor of the “gridiron gossip” column says: Manager McCutchen’s “hunch” will prove a “bum steer.”
   
27 April 1902, Fort Wayne (IN) Morning Journal-Gazette, pg. 10, col. 2:
He catches a job behind a rag counter and some wise Johnnie gives him a bum steer about being good and he starts in to relate his experiences.
   
2 May 1902, Lincoln (NE) Evening News, pg. 4, col. 4:
Mr. Alphin has an expansive smile and a surplus of avoirdupois, which might recommend him in packing house circles, but the folks in Kansas gave him a bum steer when they told him he was a base ball pitcher.
 
14 July 1904, Decatur (IL) Daily Review, pg. 3, col. 2:
Harry doubtless had a hunch that Rock Island had a swatting bee on tap, and he wished to get out from under before the pyrotechnics were touched off, but subsequent events proved that he had been handed a bum steer.
 
22 February 1905, Cedar Rapids (Iowa) Evening Gazette, pg. 9, col. 2:
One Johnson, alleged gay Lothario, was sought after by Constable Root, and it was not until two fellows of that cognomen had been arrested and unidentified that the officers came to the conclusion that the name of “Johnson” was a “bum steer.”
   
30 October 1906, Fairbanks (AK) Daily Times, pg. 3, cols. 1-2:
Money in Red Steer; Not
a “Bum Steer,” at That
 
28 March 1910, Syracuse (NY) Post-Standard, pg. 8, col. 1:
The latter, to use the vernacular of the turf, gave one and all “a bum steer” on the possibilities of both horses.