Your Least Favorite Book

What is your least favorite book that you've read all the way to the end?  I've been thinking about it, and I think for me it's a toss up between two:

"Place and Power" by Ellen Thorneycroft Fowler
"Nature's Serial Story" by E.P. Roe

Both of these books had very nice covers, though.

As a corollary, what is the book that was so bad you just couldn't finish it?  Again, I have two candidates:

"Westways" by S. Weir Mitchell 
"The Green Hat" by Michael Arlen