While shelters and fosters give the best history, you can also read many signals during meet-and-greets. Healthy grooming and relaxed behavior are strong clues, though some well-cared dogs may be stressed by new settings.
Positive indicators:
Ask about medical records, vaccination history, and recent deworming or flea treatment. A vet check shortly after adoption fills in gaps. Keep in mind that some dogs improve quickly in a stable home, so lack of perfect manners alone doesn’t mean poor previous care—context and follow-up matter.