I am sure that you have read on here that it's not good to buy from those places as they ewilll just get more in when those are sold. However, if you are set on rescuing one (which I would be too) make sure you choose the healthiest looking one. When I went to choose Amy (from a private breeder), there were 3 females to choose from. One was very dark and brown which I instantly avoided and I think another had something not quite right with it's eye. I chose Amy as she looked the healthiest and also for the fact that she had the same butterly shaped pattern on her side that my Lily had. If I remember correctly, JannB's Luie came from a Petco store or similar and he certainly turned out good!
I know how you feel though - when I went to view Tommy he had a large ficus with no leaves on and a big branch with fake ivy leaves and that was it. He looked healthy enough and did have a makeshift dripper that I presume he used, as well as a filthy looking water pot that was binned the minute I got him out of that house! Also the owner was confused when I mentioned misting - apparently he just 'flicked' water at Tommy occasionally! Needless to say, I couldn't wait to get my gorgeous boy out of there and less than 24 hours later he was in my car on the way back to my house! He is now a pampered cham and is treated like a little prince!