I think part of it is not having a good system for rating photos. I tend to 3 star anything I like and then occasionally give a 4 or 5 star to something really good, but I should use it more rigorously than that, and perhaps delete anything that doesn't get a star at all. I'd love to hear how other people get around the issue of taking thousands of photos and dealing with them afterwards without just buying more and more hard drive space!
However I must admit it feels a little cleansing to start with 150 photos in a folder and whittle it down to 50. It makes the browsing experience much more pleasant certainly! It's probably also good to realise that while it's great to make the most of digital and take lots of photos from different angles of the same scene, it's better to take time at the taking and get it right with one or two shots. Something I'm learning as I progress in my studies perhaps...
But there are some photos that are keepers no matter what technical quality they are... my son must be the most photographed little boy ever (or close to...)