Literally they're hot, but I've seen the color infrared. It's a color just like gamma rays are. I've seen every primary color of the EM spectrum. Making realistic divisions between frequencies so ast o not create -ish-type shades.. there are like 100 colors. Infrared is as to red as pink is to orange. It's like a weird black color I cannot describe. X-rays have a little hook-like shape that belong with the color itself. Like if the Dr were beaming Xrays into your head.. the shape tessalates along with the beam. It's weird. Same with gamma, and beyond. It goes on and on. When you see IR, you see everything looking back at you. All bugs, dogs, everything, and it's truly not for the weak-hearted.