Drop this in a theme's functions.php file and then resave every post/page. On saving the post/page, any inline styles will be wiped out.

crap-cleaner.php

<? php //remove this line

/**
 * This function removes all the inline style markup from posts/pages on save.
 *
 * @todo  Remove this code prior to site launch
 */
add_filter( 'wp_insert_post_data' , 'filter_post_data' , '99', 2 );
function filter_post_data( $data , $postarr ) {

    $content = $data['post_content'];

    $content = preg_replace('#<p.*?>(.*?)</p>#i', '<p>\1</p>', $content);
    $content = preg_replace('#<font.*?>(.*?)</font>#i', '\1', $content);
    $content = preg_replace('#<span.*?>(.*?)</span>#i', '\1', $content);
    $content = preg_replace('#<ol.*?>(.*?)</ol>#i', '<ol>\1</ol>', $content);
    $content = preg_replace('#<ul.*?>(.*?)</ul>#i', '<ul>\1</ul>', $content);
    $content = preg_replace('#<li.*?>(.*?)</li>#i', '<li>\1</li>', $content);

    $data['post_content'] = $content;

    return $data;
}