How are your foster dogs treated in your household...? Do they have the same rules and privileges as your own dogs...or do you set different rules up for them?
My own fosters have much more structure in life than my own dogs. For example: my foster dogs are not allowed on the furniture (bed, couch, etc); they stay in crates when I'm not around or can't supervise them; they are fed downstairs in their crates (not in the general population)...unless I'm specifically testing out how they are with food guarding around other dogs); and are treated more like second class citizens around here (not in a bad way).
They DO get to be out and about in the yard for playtimes, they are allowed out in the house to play with toys and chewies...both under supervision. They go to flyball tournaments with us, they go to training classes with me, they go with me to play with other dogs when I'm doing dog-walking...they learn their basic stuff: sit, walking nicely on a loose leash, basic manners.
I don't allow them to develop potentially bad habits, and we work hard on getting rid of bad habits...but this to me means structure and rules...not spoiling them and allowing them privileges that they haven't earned. When they go to their new home, the OWNERS can decide if they want them in the bed, or on the couch, or whatnot...
I bring this up, because I've seen a lot of foster dog pics on FB on friend's pages that show foster dogs just lounging around in their foster mom's beds, or doing something I find obnoxious. Just because they're in rescue, imho, doesn't mean they can just get spoiled and not learn anything.