As Prior says, as long as you are engaging in Deer Management, culling bucks/does/kids is doing good to the natural population and survival of its species (since its natural predators are long gone), the second you are doing it only for a trophy, for the stalk, or to pull the trigger, it's exploitation! I fully agree, and even though I started out shooting for the more 'fun and excitement' element, I have grown to take deer management more and more seriously, and will now be happy letting a nice six-pointer move by, should it be a beast in his prime who complements the population I am trying to sustain/build.
The more I learn about which deer to cull, what to look for in a healthy population, how to calculate the right sex-ratio and age demographics on my grounds, etc. the more I enjoy the sport, and the better I feel shooting deer. My personal goal is to manage the deer on my grounds, but 'treat' myself to two nice buck trophies per annum (if 'I' can) at most. ...along with whatever else the annual management plan may produce, which may include a few 4 pointers, even some old 6 pointers...but I will only take up to 2 'prime' bucks pa..just to clarify.
As for foxes, well, it's how I feel on the day. I'm not going to kill every fox just because its a predator, but I am going to take the ones that are in excess of my perceived capacity of natural balance, and will opt for the ones in poorer condition, or the ones pestering my release pens. will I shoot an elegant fox sitting in the sunset with its pup's or resting in the last rays to get warm,,,no. I also believe that if I have a clean miss on a deer, to let it go,,I've had my chance, I lost, it won. fight another day