Lindsey's hair does get dry easily, but that is more due to the fact that she was made in 2001-2002. She and the older #21s have thick curly hair which is more prone to frizz and overall dryness. We often complain that dolls like Rebecca have thin hair, but the truth is that the thin hair makes for better curls and better upkeep of the curls.
My Lindsey's hair kept its curl. I did find that the few times I slept with her really matted the curl down. However, I was able to finger-curl her hair back to its original state. What I couldn't tame was the dryness. I wish I'd known about braid spray back when I got her originally as that would've helped prevent the dryness in the first place.
So I got her a new head, and her hair is still pretty silky (although thicker than the newer dolls' curls). I haven't really touched it, but when I do, I'm going to use braid spray. I'd like her hair not to get quite so dry again.