You'll get varying opinions on this, but I'm on the side that says a well-scored word list is not important to getting a good fill. What is important is doing the fill word-by-word and selecting only words that are "good" whenever possible. Depending on the software you're using you may be able to (while you're doing a fill) delete bad words from the word list, put a higher score on words you like and a lower score on ones you don't like.
The reason those lousy words have 50 points is because that list started out with every word having 50 points, and someone changed the scores of some tiny fraction of the 300K or so words that are in the list. I honestly can't imagine anyone going all the way through one of those massive word lists and assigning a "proper" score to each one.
Every time I fill a puzzle, a knock words out of the word list that come up but are obviously not usable. Hundreds of puzzles later they're still coming up (not the ones I knocked out, but their replacements)! Just keep scrolling down until you find one you can use.
