I think because I just read a really excellent book (Catching Fire), it makes me less willing to read books that I don't like, and so I'm more likely to give up. After awhile this fades, and I'll put up with a little more. So I have a couple of DNF's (did not finish).
The first is The Forever War by Joe Haldeman. I know this is classic science fiction, and I think it won awards and stuff, but I just don't care. I don't care about any of the characters, I don't care what happens in the plot. I think I'm about 150 pages in, and I'm gonna stop reading it.
The other was Shiver by Maggie Stiefvater. I've read so many good reviews of this, but I got about 25 pages in and just couldn't handle it anymore. The girl talking about "her wolf" over and over got on my nerves. The prose got on my nerves. And I realized this is another Twilight. Not that the story is the same (although it kind of is), but that so many people love and adore Twilight, and I thought it was blah and not very well written.
Right now I'm reading Fablehaven, and it's getting me out of the "I just read an awesome book and everything else is crap" slump.