Yes, you need to be clean shaven and you WILL KNOW, very painfully, if you missed a spot. The hair explodes and it's not pleasant. Smells wonderful too

If this is your first go around with laser, and they are using a good laser, be prepare for it to hurt. A lot. A lot a lot. Before you go, you might want to take some anti inflammatory Like Motrin or similar, and put on hydrocortisone cream as soon as you get in the car. I was red, puffy and in a lot of pain for about three days after my first session. Now after five it's more like a day, but still a few days before shaving is comfortable again. For this reason, I schedule my laser appointments for Friday mornings and work remotely, then by Monday I'm pretty well back to normal. I actually got outed by someone because they recognized the swelling as laser.