I had a little 3 or 4 month old puppy follow me from my neighborhood all the way to campus when I was graduating, about a mile and a half walk. I kept trying to get it to go home, but alas, it followed me. It didn't have a collar, but it looked really healthy and cared for, and was pretty well socialized, so I knew it shouldn't really be a stray. I had to go in for graduation, so I gave the puppy so a security guard for the duration, and picked it up when I was done. Tied my purse strap to it and walked it back home, knocking on all my neighbor's doors. No luck, the puppy stayed with me for the night, and the next day as I was putting up "found" signs, the owner saw me and claimed the dog.
I was so sad to give the pup back, the owner obviously was very irresponsible. No collar, no petting of the dog, just casually asking how I'd found the dog, no thanks or anything, just yanked the dog down the street.