I find that what often FEELS like crap when I'm writing, isn't crap when I go back to edit. But I use a lot of place holders and such. I leave myself messages in the ms as I write. I simply click the caplock and type ADD DESCRIPTION OF HOUSE EXTERIOR.
I just plow on through.
Definitely this.
I often find what I felt was arsewater of the finest grade when I was writing it turns out to be merely in need of a tweak / cut down a bit / padded out a bit when I go back to it later. I also find out the longer I leave it to mellow in my box file (ahhh, my box file... love my box file!), the better disposed I am to it, kind of like a rather tart red wine that needs to breathe a bit before it is palatable. That's not to say the first draft is Dickensian genius of the highest order when I go back... it's just that is wasn't quite the hideous beast I was convinced it was when I first wrote it.
I have recently become a devotee of the CAPSLOCK REMINDER. It really has saved my sanity on more than one level.
(I have officially made that certificate my wallpaper now. Each time I flounder, I am going to look at it and remind myself that Uncle Jim says it's okay!)