Guru hints not working in pgAdmin
you will find valuable information in pgAdmin III documentation, and to be more precise in the settings page about miscellaneous options. You can check that Guru hints are enabled (unchek the Do not show guru hints; I’m one myself box if it's checked). You'll notice that guru hints won't be available everywhere, but only on some objects in you database, for example tables (saying something like "hey, what about defining a primary key for this table?"), functions and so on.

Good luck!