honey pot field and conditional submit

Hi, your reply may be in general terms. This is a strategy question. I have a form with basic contact info fields. I have a field named Address that I have hidden with css (display:none) that will be a honey pot to catch the robots that fill in and submit forms. Humans cannot see this field but robots will see and fill it in. So I need a strategy where the form is only submitted if this field has my default value in it and is unchanged. How can I do a conditional submit, depending on the value of the Address field?