Title VIII of the Civil Rights Act of 1968 is commonly known as the Fair Housing Act and was a follow‑up to the Civil Rights Act of 1964.
The Civil Rights Act of 1866 prohibited discrimination in housing, but there were no federal enforcement provisions.
The 1968 act expanded on previous acts and prohibited discrimination concerning the sale, rental, and financing of housing based on race, religion, national origin, and since 1974, gender; since 1988, the act protects people with disabilities and families with children.
I don’t think that pets & smokers fall into the above.
Being a landlord comes with huge responsibilities.
Luckily for most landlords, most tenants do not know their rights.
It can be dangerous in casual conversation to mention sexual preference, religion, pregnancy, ethnic origin etc. and then deny an applicant.