The wife and I went for a ride today and after getting to our destination, I get off the bike and go around to the right side of the bike and find black rubber on the exhaust system.
I ask my wife to check her boot and it is partially melted. She said she was stretching her leg and letting it hang down for a while, and I guess it was rubbing against the pipes.

How do I get this off now without scratching the pipes?

A buddy used Easy-Off oven cleaner with good results. I think the sooner-the-better. The more you ride, the more you'll bake on the rubber. JMO

+1 on the easy off. It works best if the pipes are warm.

What works for me:
1. When hot, use a thin, flat piece of wood to scrape as much soft residue off.
2. Once cooled-down, use 000 steel wool with a solvent such as goof-off to remove the remaining residue/stain.

I guess that's one way to burn rubber.
Also suggest moderate use of a propane torch or heat gun to soften the goop as you scrape.

Taken fresh rubber & plastic off hot pipes with a cold really wet towel , haven't lived till somebody's plastic cover tarp comes off the pickup and you can't dodge it , friggen melted plastic everywhere. Get the bike hot let it idle and get a normal sized towel with a bucket of cold water, drunk the towel and wipe , knock the chunks off the towel and repeat till it's gone. Chrome cleaner for finish work.

Easy off oven cleaner, make sure they are cold, cover all other items, spray, leave over night, hose off

If you use Easy Off make sure you spray it on a towel and apply it to the pipes using the towel. Easy Off WILL ruin your painted surfaces. It's not worth it to "try your best" not to get overspray all over the place.

Im guilty..not sure how I did it.
but I discovered black residue on my pipes after a ride.
then discovered a melted spot on heel of my right boot.