The only time you'll be able to spot a trailcam by the infrared flash is when it flashes.
If you're close enough, you can often see a very dim red glow and if you are quiet enough, you may even hear the little click of the shutter. If you have on night vision goggles however when it flashes, it will look like a flash of lightning or one of those old timey ice cube looking flash bulbs going off that make you see spots for 2 minutes.
For what it's worth, I don't know why anyone in their right mind would want to take naked pics of you though. That just seems all wrong to me.