I'm sure many people know this, but, the ones from Walmart they suck.
They leave fibers everywhere, and will make your car look like it's covered in micro-hair...
Washing them doesn't help either.
On the other hand, these are great!
Zaino Blonde Borderfree Towel: 3 pack: Zaino Store
Dried my whole car with them (all 3), let them dry off, and used the cleaner looking one with some quick detailer to get water spots off...no problem...
Also, I've used these for windows - they work well and leave zero lint:
Twelve Micro Fiber Wipe-Down Towels - Drying - Car Care - Griot's Garage
I also used this to wash my Z, no scratches.
Micro Fiber Wash Mitts or Pads - Cleaning Tools - Car Washing - Car Care - Griot's Garage
I have a black Z...I notice scratches very easily.. =/