Many rescue dogs make wonderful companions but buyer beware. Don't believe everything you are told and try to observe behavior beforehand particularly around children and other pets.
I came home to find a four legged squatter, a miniature schnauzer cross, in my yard. My wife had gotten him off cl from supposedly an elderly woman who was moving into a care home. Became quickly apparent that he had issues, he had a hate on for men. He would block the doorway and bite if I tried to pass, would snap for no apparent reason yet other times he was the sweetest most playful dog. He was also miserable with the other dog. We finally had enough and gave him to a trainer who had to put him down, the vet figured he was having seizures.
We now have a second toy poodle who appears to been badly treated. She is very submissive, pretty much ignores me, but follws my wife everywhere.