Any CCD camera that doesn't have the ruby-colored filter over the chip is IR sensitive.
IR illuminators can assume the intensity of a spotlight without anyone knowing.
Some clothing is see-thru by simple flash photography.
Some fabrics are IR-transparent.
Can you put that all together? Ok, then let me throw this in... you can get unfiltered CCD cameras from just about anywhere online, raw packages (no case, etc... just circuit boards) for ~$40. I know, I use one for an inspection camera at home, they're real handy to drop into vents to see just what died down there, stick 'em behind the furnace to see just what died back there, spaces behind walls to see what the previous owners stuck back there, etc.