Most of the IR trail cameras show a red glow and still catch the attention of most Deer,the Black-flash trail cameras are suppose to be better and less detected by Deer.The trick is to set a Camera up higher and aim it downward to be less detected by the Deer!
Some trail cameras give off a click or shutter sound when the camera is triggered...this can scare the Deer just as bad as a flash.As Pnut mentioned some Deer aren't as scared of the old white flash trail cameras as some mention...I also have an older Cuddeback Capture (white flash) Camera that has a fast shutter/trigger speed and have caught many nice Bucks on it and still works great and hasn't scared the Deer away!