Also do they understand the costs
I agree with trying to reason with them about the lack of time & offer them $ if necessary, but I would definiately bring up the cost of even just reg vet vists, Heartguard, Frontline Plus etc, not to mention the possible emergencies that may arrive! Plus a good quality food, toys, equipment (collars, leashes, id tags etc) city license, all of these things really add up and not to be ornery but if you really think this is not an appropriate home for a Boxer Babe I'd lay it on really thick, give them the guilt trip, I visit our local humane society weekly & see the lame excuses of "too big" "too much energy" etc, etc, so do the best you can to make sure she he will be given the best chance possible. : )
Good luck!
Jackie & Zoe