This is an awesome and annoying feature of current systems. It pulls all your contacts into one place but it also pulls all of your contacts into one place lol. FB contacts are the worst. I'm way OCD about this stuff, but I've resigned myself to just not think about it, as cleaning it up would be insanely time consuming. If I need to contact someone I look them up. If the contact has a bunch of crap or duplicates I delete it at that time.
If you are in the mood for some learning you could batch them in Access to remove info and export to a CSV Excel. Access isn't all that hard to learn and I think is actually easier to use for data mining/manipulation than Excel.