I've used the SL to ignite toilet paper. It took about 5 or 6 strikes, very close, IN THE SAME LOCATION. (Just in case you're one of those people who like to move the match around and try different spots.) After 3 or 4 strokes, the paper turned brown; another 1 or 2 strokes after that ignited it.

The TP had been left out overnight, but underneath an army surplus parachute shelter, so it wasn't wet but may have been slightly damp.

I just tried it with a dry cotton ball (no vaseline). I made no attempt to fluff the cotton ball, I just left it as is, held the SL about 1 cm away (my first attempt resulted in the cotton being caught by the rotating wheel and dragged inside but it didn't seem to cause any damage.) Three quick flicks and the cotton ball began burning.

For a FeCe rod, a Blastmatch or Swedish Firesteel, or a Mag-Flint type lighter I would probably recommend fluffing up the cotton ball, because those items release a large shower of sparks. But for the SL, it seems to work better if you have a specific area that you can concentrate the sparks on. MHO only, of course, and bear in mind that I have far less experience than most of the others who responded. Still, what works, works.