I'll always sign the message that contains the bitcoin address for all of my escrows. It is generally a good idea to verify that signature if you can so that you know that the message came from me. If I ever give anyone a bitcoin address to send bitcoins to for any reason and they aren't 100% certain that I'm the one that sent it, then simply ask me to sign it. I'm always happy to provide that assurance.
There are a lot of scammers on this forum (that's one of the reasons that people choose to use an escrow provider in the first place). Always make sure that you verify the identity of anyone that is asking you to send the bitcoins to make sure that you are actually communicating with the person you think you are and not an imposter with a similar ID. If you don't have their public key, or they don't know how to sign messages, then at least check the trust feedback and posting history.