This way you catch any email containing the target phrase. If you notice that you are getting a lot of spam from the same domain, set up a filter to automatically delete all email from this domain. Set up your email client so that mail sent to the trash is not totally deleted. You just want the spam initially filtered to the trash can. This gives you a chance to confirm that the filtered email is not something you wanted before you delete it.
Spammers often send email to bogus aliases at valid domain names.
They use programs that generate email addresses featuring valid domain names and randomly generated aliases. Many web hosts, including mine, allow you to have a dump account. This dump account forwards any email sent to an invalid alias on your domain to whatever email you specify. This feature allows you to receive email from those who might incorrectly type in your email address. This can be very convenient.