Well, speaking for myself, I think an editor's point of view is welcome.
Personally, I pride myself on generally knowing the correct grammar to use and being able to use it. Yes, I make mistakes, but I can generally understand my mistakes, learn from them, and move on. This is not the case with Lay/Lie. It is by far the construction I have the most trouble with. I generally have some trouble with affect/effect too, but I can actually usually get it right if I give it some thought. With Lay/Lie thinking about it just plain doesn't help. I have to look it up every single time and never remember for next time. I'm usually able to figure it out if I am looking it up, but learning it, just doesn't seem to work. For whatever reason I've never been able to make this one sink in.
Actually, when I was a kid I could do this with no trouble. The first time I ever learned it I picked it up right away and it stuck with me pretty much through all of grade school and junior high. By high school I was hazy on it, and from there I've never been able to relearn it such that it would stay with me. So in conclusion, by the end of puberty I was ready to get laid, but unsure if I'd been laid or lain.
Anyway, I've more or less given up; when I write I just keep a resource handy that will tell me which is correct (FYI, that resource is called Sharon )
-Kevin