postgres=# SELECT COUNT(DISTINCT s.id)
postgres-# FROM submissions s
postgres-# JOIN comments c ON s.id = c.link_id
postgres-# WHERE c.body ~* '\y(list of words from https://github.com/LDNOOBW/List-of-Dirty-Naughty-Obscene-and-Otherwise-Bad-Words/blob/master/en)\y'
postgres-$ OR s.self_text ~* '\y(same list as above)\y';
 count
--------
 254682
(1 row)

postgres=# select count(DISTINCT s.id) from submissions s;
 count
--------
 850977
(1 row)