I thought about taking a drafting lesson once. Then I watched a group drafting and realized that in no way do I want my face that close to someone else's sweaty butt.

Case closed. Don't draft anyone, espescially if you don't know them. You have no idea how much I fart when I over-exert! Just sayin'...

What? Your face isn't that close to their butt. It is quite fun done properly with folks you know.
I had a 45 min descent a few weeks ago that I spent a few inches off of my friend's wheel doing 30-40 mph. He descends like a rock and I am a wee bit on the light side.

If you want to, you can.

You should not do it if you are using aero bars. Also, remember, if anything happens,
it will happen to you. Not the leader. So pay attention.

As indicated, some are uncomfortable with it and will even try to give you the slip.

Shaved legs are a good indicator of whether or not a rdier is dedicated to the sport. I wouldn't grab the wheel of anyone whose legs are not shaved.

If they slow down too much, you can give them Madsons.

USA Cycling has ommitted the previously infamous invention of madsons, but, a madson is pushing from behind, by a team mate, in order to help the rider gain momentum.

If you have ever watched the movie Breaking Away, you have seen madsons performed as each subsequent relay rider was pushed to get going on the cinder track.