I bought a cheap infrared temp gun, and all my cylinders range at idle from 180 degrees F clear up to 280. 1,3,7, 2,6 all seem to be 180.
#8 is actually always my hottest. Clear up to 280. Then #5 and 4 are more like 220.
I too thought the exhaust tube coloring (indicator of heat) could be a helpful indicator of balance but seems it isn't so.
For meaningful comparisons need to actually the CHT or Exhaust gas temperatures, not the outsides of the tubes. :(
Moparoffial is putting you on the right path. If anything read the plugs. But basically for idle, make adjustments until runs the best. Do it with the engine hot, and if its an automagic, go by best in-gear.
