<human>: Can you give me a shortened version of the text?

**Background**
I have been fostering dogs for almost a year. I work with a Golden Retriever rescue and usually only have a dog for 3-5 weeks before they are adopted. I adopted my dog (Charlie) from the rescue last April - he was foster #4. I'm currently on foster #10. Foster 10 is named Mr. Bear and he's a sweetheart. He's a golden mix (with what? I have no idea) and is 11 months old. Hyper, happy, cuddly, talkative, and a little high-strung. His owner died, which is why he came into the rescue.

**The Issue**
Mr. Bear has been with me for about 2 months. He's generally a very good dog. There are some things we are working on (jumping up when people enter the house and counter-surfing). He is sometimes alarmed by large men, especially if they are wearing hats, but gets over that fairly quickly if they get on his level and give him some space and time to acclimate. Otherwise he's perfectly friendly and has shown that he can master tricks and obedience very quickly.

He was adopted in mid-December by a young couple who have a 4 year old lab. Unfortunately they returned him after a 4-5 days because their lab was annoyed at Mr. Bear's playfulness and the dogs weren't getting along. Recently he was adopted by a middle aged couple (kids in college) and now, after 2 days, they also want to return him because they claim he is aggressive with the Mrs.

I'm kind of at the end of my rope. I'm feeling a little discouraged because I keep choosing the wrong families for him, even after we do in person meetings to determine if it's a suitable fit. And now he's supposedly displaying behavior that I have NEVER seen from him before! Not once has he ever growled, snapped, or tried to charge a person. Even with men he was afraid of - the most he would do was bark. I'm not sure what to do - should I ask that he be placed with a different foster? Is there a temperament test or evaluation (beyond what a typical rescue does) that should be performed? What the heck is going on with this dog???
<bot>: Foster dog has burned through his second adoptive home and is now supposedly displaying aggressive behavior. What should I do for this dog?