They are not really abandoned here. People feed them and take care of them. Each soi (alley) has their soi dogs. They patrol their territory at night, and sleep in the day. Once you are known or if you walk through nicely, nothing happens. But if drunks come by or someone is out at night causing trouble, the soi dogs let everyone know by their ruckus.
When I first get to anyplace they dogs check me out since I am out at night. But once they know me they only glance up. I have a jacket with a hood and one time it was raining so I had it on at 3 am. They all came running. But I took off the hood and they all stopped, looked and walked off. My heart was pounding, and I was so glad I realized it was the hood without thinking :)
So the dogs are looking after people of the area in exchange for food, a very good system to have and to learn about.
Excellent security considering they get to know you by smell allowing you access to move around feeling safer at odd hours.