I usually compare the readings when I take hydro samples. Usually within one degree of the thermometer. Close enough for monitoring fermentation temps.
"You can't drink all day if you don't start in the morning."
Kegged - Where's Waldo Amber Ale
Dry peppering - Jalapeno Wheat
On the fruit - Currant Wheat and Huckleberry Wheat
Primary - FUBAR Weizenbock and Accidental Dunkelweizen
Hops - Centennial, Nugget, Mt. Hood, Cascade, Willamette, Magnum, Chinook