Mlp_Unhook.php

<?php
/**
 * Remove callbacks for problematic hooks.
 *
 * Many plugins and themes do not check for a switched site context, they will
 * save $_POST data to the wrong site. This class tries to remove all those
 * callbacks.
 *
 * @version 2014.07.23
 * @author  Inpsyde GmbH, toscho
 * @license GPL
 */
class Mlp_Unhook {

	/**
	 * Register the unregister callback.
	 *
	 * @return void
	 */
	public function setup() {

		$hooks = $this->get_hooks();

		foreach ( $hooks as $hook )
			add_filter( $hook, array ( $this, 'remove_all_callbacks' ), -1 );
	}

	/**
	 * Runs on every single hooks and removes everything attached to it.
	 *
	 * @param  mixed $input Any parameter provided as the first one.
	 * @return mixed
	 */
	public function remove_all_callbacks( $input ) {

		if ( ms_is_switched() )
			remove_all_filters( current_filter() ); // covers actions too.

		return $input;
	}

	/**
	 * Collect all possible hooks.
	 *
	 * @return array
	 */
	private function get_hooks() {

		$hooks = array (
			'pre_post_update',
			'save_post',
			'wp_insert_post',

			'pre_insert_term',
			'edit_terms',
			'edited_terms',
			'edit_terms',
			'edited_terms',
			'create_term',
			'term_id_filter',
			'created_term',
			'add_term_relationship',
			'added_term_relationship',
			'set_object_terms',
			'edit_term_taxonomy',
			'edited_term_taxonomy',
			'wp_update_term_parent'
		);

		$post_types = get_post_types();

		foreach ( $post_types as $post_type )
			$hooks[] = "save_post_$post_type";

		$taxonomies = get_taxonomies();

		foreach ( $taxonomies as $taxonomy ) {
			$hooks[] = "create_$taxonomy";
			$hooks[] = "created_$taxonomy";
		}

		return $hooks;
	}
}

usage.php

<?php
add_action( 'plugins_loaded', [ new Mlp_Unhook, 'setup' ] );