Grep multiple pattern negative match

You can try:

grep -vE 'Googlebot|msnbot-media|YandexBot|bingbot' yourlogfile

If there is an empty line in the patterns file it will match every line, causing no lines to be returned with -v. This is because the lines are interpreted as regular expressions, and an empty regular expression will always match.

This isn't a problem with -F however, because grep ignores empty lines with -F.
-F causes grep to interpret the lines as simple strings to search for and may speed up grep if regular expressions aren't needed.