Detecting corrupt table

Our database has some corrupt tables and I'm trying to figure out what data
can be salvaged and what needs to be restored from backup or regenerated.

Initially I tried running select count(*) on all user tables. While this
did detect some corrupt tables, it missed others. For example, I was able
to run count(*) on a table but then got an error while trying to back it up.

pg_dump: Error message from server: ERROR: missing chunk number 0 for
toast value 368243665 in pg_toast_284730161
pg_dump: The command was: COPY public.stories (stories_id, media_id, url,
guid, title, description, publish_date, collect_date, story_texts_id,
full_text_rss) TO stdout;

Is there a simple way to determine which parts of the database are corrupt?
I'm currently running a script to back up each table individually using
something like the following:

psql -c "select tablename from pg_tables where tableowner = 'db_user' ORDER
by tablename " | tail -n +3 | head -n -2 | xargs -n 1 -i pg_dump --verbose
--table={} --file={}_.dump

But I'm worried that this approach will also miss database corruption and
was wondering if anyone has other suggestions.

Thanks,

David