What do do about face book friends - this may be a dumb question?

I was looking through the list of people proposed to me as friends - mainly on the grounds that we knew the same people. Some were people I knew. Some were people I'd met once or twice. Some were people whom I might have met, but certainly wouldn't want to offend by rejecting them as friends. Some people I might have chatted to on mudcat. Others I sinply didn't have a clue - not even which friends we held in common.

So you could tick everybody to be your friend. But that seems insincere. Or you could dicriminate, but I'm not sure how.

And there are such a lot! What do other people do?