I... Sometimes adopt literate pups I've seen around and roleplayed with several times (many are usually just one-time characters!). It's how I met one of my current roleplaying parters-- I adopted her character a fair few months ago and we've been roleplaying daily together ever since!
Sadly, most of the time, the pup never logs in again-- or it's an utter disaster (my most recent one grew to adult within the hour and flirted with her adoptive father). Even so, the times it does go fantastic makes it worthwhile! There's no harm in it, really, minus the occasional spamming and begging.
I'll whole-heartedly admit to keeping my eye out for homeless pups (and looking for homes on my own pup-character!).