In all honesty, I could pretty much guarantee that your Porsche has scratches from washings and using a cotton cloths on them.......just saying.
Maybe, but then I've never owned a black car and will never own another dark coloured car again as you see everything on them. All car finishes get scratched or we wouldn't be re-polishing them, even the ones using magical drying cloths.
As with many things, they are preying on our fears. Really, a $1 patch of cloth made off-shore costing $20.

I'll bet you could find those in a non-auto package for a lot less.
I prefer spending my coin on polishes, etc where there is a much bigger difference in performance between consumer and professional grades.
BTW, since everybody is pushing a store, I get my stuff at AutoGeek. They have sales and free shipping from time to time. The exchange rate is a bonus at the moment.
http://www.autogeek.net