Summer in California asks:
Do I need to ask permission from the realtor, or homeowner to use the photos I take of their listing for my own marketing (website, social media, mailers, etc.)?
There are two parts to the answer to your question:
Photos taken from a public place (like a street) do not require a property release from the owner see: the PhotoAttorney.com site.
For interior photos the ASMP recommends the following: Look at the photograph and ask these questions:
If the answers to #1, #2 and #3 are no then you do not need a release. However, according to Photoattorney.com case law relating to property releases indicates there has never been a case that has shown the requirement for a property release. For this reason, many real estate photographers don't bother with property releases.
However, I think there is a good argument for using a property release just for the purpose of being courteous to the homeowners. Many people get very sensitive about their personal space.