Maddy is our current chocolate foster. She's about 5 yrs old and has a fair bit of gray on her already. Even her eyebrows are gray which sometimes gives her an "angry" appearance. She definitely does not act old though.
Maddy is one of those all-around fitting dogs. Most of the rescue dogs have certain preferences (w/o other dogs, prefers dog, low-energy, likes children, etc) when we place them. Maddy seems to adjust to pretty much everything. Overall she's extremely mellow in our house because we tend to be low-energy. She's happy either finding a dog bed or laying right next to your seat for the occasional petting. She is very sweet and just loves people, she's also a HUGE licker and always goes straight for the face.
I think I'd like Maddy a lot more if she wasn't so pushy about attention for herself. I can give her tons of attention but as soon as I go to pet Sheba, Maddy is all over us and she's pretty intent on getting all the attention for herself. She'll wedge herself between Sheba and I, then wiggle her whole body to knock Sheba out of the way. If Sheba is laying on the ground while I'm petting her, Maddy will walk all over Sheba to get closer to me. Mike and I have taken to either keeping her at arm's length when we're petting Sheba or double-teaming her. One of us will keep Maddy occupied while the other one will pet Sheba. I guess I feel pretty protective about Sheba so anything that causes her more discomfort makes me upset.