Reminds me of a great article in Dragon magazine years ago that addressed these issues:

1) Boss monsters scatter their treasure all over the dungeons in bits and pieces instead of gathering it all in one place.

2) Boss monsters often live in rooms that have exits too small for them to get out of.

3) The party always happen to be in the right place at the right time to get details of their next quest. You never have the adventurers hanging around the pub for a few weeks and killing time.