Does wp_insert_post sanitize/validate input?

Hello everyone, thanks in advance for any help.

I was just wondering if data thrown into the database with wp_insert_post() and add_post_meta was automatically validated/sanitized by WordPress.

I ask because I have been trying to write some sanitation/validation functions before putting my data into each function, but came across the following today:

$wpdb->insert( $table, (array) $data )
$data should be unescaped (the function will escape them for you). Keys are columns, Values are values.

To me it seems to imply that WordPress automatically validates/sanitizes data before putting it into the database, however I don’t really understand what it says all that well…

Thank you again