I would like to encourage everyone to leave comments on your guests and hosts on Warmshowers. There really aren't enough comments out there. If someone is going to be a great host / guest then everyone should know it. Likewise if someone is a lousy guest / host then EVERYONE should know.
It would be nice if Warmshowers developed a similar model to Couchsurfing. In Couchsurfing, folks can be vetted by a local rep. It would sure be nice to know that you that you aren't rolling into home of the local ax murderer or inviting one into your home.
I was very shocked when I was in Italy, I stayed at the home of two families that had young children. If I had children, I am not so sure I would invite a male stranger into my home but I guess they are more trusting.