CO is fined thousands of dollars every year for a variety of Immigration problems. No visas, incorrect visas, unreadable passports, expired passports and passports that look like they have been tampered with. Suspected tampering can be anything the Official wishes it to be; ink bleeding, plastic coating bubbling, tears on the face page which might mean that the photo has been removed or substituted.
We are required to inspect your passport. We do not wish to see you stopped, delayed or refused entry in your next foreign destination. Some countries are stricter than others.